diff --git a/README.md b/README.md
index 21543fe..830d162 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ browser ──nginx (basic auth, TLS)──▶ /api/* ─▶│ SQLite       │
 - `public/`: static frontend (no build step). Add `?mock=1` to the URL to use built-in sample data.
 - `backend/`: FastAPI API backed by a single SQLite file.
 - `deploy/`: nginx site and systemd unit.
-- `collectors/`: scripts that report results from backup products ([Veeam B&R](collectors/veeam/README.md), [Azure Backup / MARS](collectors/mars/README.md), [Windows Server Backup](collectors/wsb/README.md)).
+- `collectors/`: scripts that report results from backup products ([Veeam B&R](collectors/veeam/README.md), [Azure Backup / MARS](collectors/mars/README.md), [Windows Server Backup](collectors/wsb/README.md), [Veeam Backup for M365](collectors/vb365/README.md)).
 
 ## Data model
 
diff --git a/collectors/vb365/Get-Vb365CollectorDiagnostics.ps1 b/collectors/vb365/Get-Vb365CollectorDiagnostics.ps1
new file mode 100644
index 0000000..40d818e
--- /dev/null
+++ b/collectors/vb365/Get-Vb365CollectorDiagnostics.ps1
@@ -0,0 +1,119 @@
+<#
+.SYNOPSIS
+    Read-only dump of what the Veeam Backup for Microsoft 365 cmdlets return, for troubleshooting
+    the collector.
+
+.DESCRIPTION
+    The collector reads properties of Get-VBOJob / Get-VBOJobSession results whose names aren't
+    fully documented. This prints those objects' real structure (property names, types, values and
+    each date's Kind, a few levels deep) for a few jobs and their latest sessions. Nothing is
+    changed. Output is also saved to a text file.
+
+.EXAMPLE
+    .\Get-Vb365CollectorDiagnostics.ps1
+#>
+[CmdletBinding()]
+param(
+    [int]$Jobs = 3,
+    [int]$SessionsPerJob = 2,
+    [string]$OutFile = (Join-Path $env:TEMP 'vb365-collector-diagnostics.txt')
+)
+
+$ErrorActionPreference = 'Stop'
+$MaxDepth = 4
+
+if (-not (Get-Command Get-VBOJob -ErrorAction SilentlyContinue)) {
+    if (Get-Module -ListAvailable -Name Veeam.Archiver.PowerShell) {
+        Import-Module Veeam.Archiver.PowerShell
+    } else {
+        Import-Module (Join-Path $env:ProgramFiles 'Veeam\Backup365\Veeam.Archiver.PowerShell\Veeam.Archiver.PowerShell.psd1')
+    }
+}
+
+function Test-Scalar($Value) {
+    return $null -eq $Value -or $Value -is [string] -or $Value -is [ValueType] -or $Value -is [guid]
+}
+
+# Recursive "name (type) = value" listing. Collections show their first 3 items.
+function Show-Object($Value, [string]$Indent = '  ', [int]$Depth = 0) {
+    if (Test-Scalar $Value) { return }
+    if ($Depth -ge $MaxDepth) { "$Indent..."; return }
+    if ($Value -is [Collections.IEnumerable]) {
+        $items = @($Value)
+        "$Indent[$($items.Count) item(s)]"
+        $i = 0
+        foreach ($item in $items | Select-Object -First 3) {
+            "$Indent[$i] ($($item.GetType().FullName))$(if (Test-Scalar $item) { " = $item" })"
+            Show-Object $item "$Indent    " ($Depth + 1)
+            $i++
+        }
+        return
+    }
+    foreach ($p in $Value.PSObject.Properties) {
+        try { $v = $p.Value } catch { "$Indent$($p.Name) = <error: $($_.Exception.Message)>"; continue }
+        $type = if ($null -eq $v) { 'null' } else { $v.GetType().FullName }
+        if (Test-Scalar $v) {
+            $kind = if ($v -is [datetime]) { " [Kind=$($v.Kind)]" } else { '' }
+            "$Indent$($p.Name) ($type) = $v$kind"
+        } else {
+            $text = [string]$v
+            if ($text.Length -gt 100) { $text = $text.Substring(0, 97) + '...' }
+            "$Indent$($p.Name) ($type) = $text"
+            Show-Object $v "$Indent    " ($Depth + 1)
+        }
+    }
+}
+
+function Show-Section([string]$Title, [scriptblock]$Get) {
+    "== $Title"
+    try {
+        $result = @(& $Get)
+        if ($result.Count -eq 0 -or ($result.Count -eq 1 -and $null -eq $result[0])) { '  (nothing returned)' }
+        $n = 0
+        foreach ($item in $result) {
+            if ($null -eq $item) { continue }
+            "  [$n] ($($item.GetType().FullName))"
+            Show-Object $item '      '
+            $n++
+        }
+    } catch {
+        "  error: $($_.Exception.Message)"
+    }
+    ''
+}
+
+$report = & {
+    $module = Get-Module Veeam.Archiver.PowerShell
+    "Generated $(Get-Date -Format o) on $env:COMPUTERNAME, PowerShell $($PSVersionTable.PSVersion), module $($module.Version)"
+    "Local time zone: $([TimeZoneInfo]::Local.Id), UTC offset now $([TimeZoneInfo]::Local.GetUtcOffset((Get-Date))), culture $([Globalization.CultureInfo]::CurrentCulture.Name)"
+    ''
+    "== Organizations"
+    try {
+        Get-VBOOrganization | ForEach-Object { "  $($_.Name)  [$($_.Type)]" }
+    } catch { "  error: $($_.Exception.Message)" }
+    ''
+    $allJobs = @(Get-VBOJob)
+    "== Jobs: $($allJobs.Count) in total"
+    $allJobs | ForEach-Object { "  $($_.Name)  [$($_.Id)]  enabled=$($_.IsEnabled)  next=$($_.NextRun)" }
+    ''
+    Show-Section "Get-VBOJob (first $Jobs, full detail)" { $allJobs | Select-Object -First $Jobs }
+    foreach ($j in $allJobs | Select-Object -First $Jobs) {
+        Show-Section "Get-VBOJobSession -Job '$($j.Name)' (latest $SessionsPerJob)" {
+            Get-VBOJobSession -Job $j | Sort-Object CreationTime -Descending | Select-Object -First $SessionsPerJob
+        }
+    }
+    if (Get-Command Get-VBOCopyJob -ErrorAction SilentlyContinue) {
+        Show-Section 'Get-VBOCopyJob (first 2)' { Get-VBOCopyJob | Select-Object -First 2 }
+        if (Get-Command Get-VBOCopyJobSession -ErrorAction SilentlyContinue) {
+            Show-Section 'Get-VBOCopyJobSession (latest 2)' {
+                Get-VBOCopyJobSession | Sort-Object CreationTime -Descending | Select-Object -First 2
+            }
+        }
+    } else {
+        '== Get-VBOCopyJob: not available'
+    }
+} | Out-String -Width 300
+
+$report
+$report | Set-Content -Path $OutFile -Encoding UTF8
+Write-Host "Saved to $OutFile"
diff --git a/collectors/vb365/Install-Vb365Collector.ps1 b/collectors/vb365/Install-Vb365Collector.ps1
new file mode 100644
index 0000000..b11e1fd
--- /dev/null
+++ b/collectors/vb365/Install-Vb365Collector.ps1
@@ -0,0 +1,105 @@
+<#
+.SYNOPSIS
+    Installs the Veeam Backup for Microsoft 365 collector as a SYSTEM scheduled task.
+
+.DESCRIPTION
+    - Copies Send-Vb365BackupStatus.ps1 to Program Files (only admins can modify it, which
+      matters because it runs as SYSTEM).
+    - Writes the config to ProgramData\BackupDashboard and restricts that folder to SYSTEM and
+      Administrators, since it contains the API key.
+    - Registers a scheduled task that runs every IntervalMinutes, under Windows PowerShell 5.1
+      (powershell.exe) unless -PwshPath points at PowerShell 7.
+    Safe to re-run to change settings or update the script. Can sit alongside the other collectors.
+
+    Dashboard company per job: -OrganizationTenants maps Microsoft 365 organization names to
+    companies; jobs of unmapped organizations use -Tenant, or the organization's name if no -Tenant.
+
+.EXAMPLE
+    .\Install-Vb365Collector.ps1 -ApiUrl https://backups.example.com -Tenant "Acme Corp"
+    One client per VB365 server. Prompts for the API key.
+.EXAMPLE
+    .\Install-Vb365Collector.ps1 -ApiUrl https://backups.example.com -OrganizationTenants @{
+        'acme.onmicrosoft.com' = 'Acme Corp'; 'bluewater.onmicrosoft.com' = 'Bluewater Dental' }
+    A shared VB365 server protecting several organizations.
+#>
+#Requires -RunAsAdministrator
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)][string]$ApiUrl,
+    [string]$Tenant,
+    [hashtable]$OrganizationTenants = @{},
+    [string]$SourceSystem = 'Veeam Backup for M365',
+    [ValidateRange(5, 1440)][int]$IntervalMinutes = 60,
+    [ValidateRange(1, 720)][int]$LookbackHours = 48,
+    [string]$InstallDir = (Join-Path $env:ProgramFiles 'BackupDashboard'),
+    # Run under PowerShell 7 instead of Windows PowerShell, e.g. 'C:\Program Files\PowerShell\7\pwsh.exe'
+    [string]$PwshPath
+)
+
+$ErrorActionPreference = 'Stop'
+$TaskName = 'Backup Dashboard - VB365 collector'
+$DataDir = Join-Path $env:ProgramData 'BackupDashboard'
+$ConfigPath = Join-Path $DataDir 'vb365-collector.json'
+$Shell = Join-Path $env:SystemRoot 'System32\WindowsPowerShell\v1.0\powershell.exe'
+if ($PwshPath) {
+    if (-not (Test-Path $PwshPath)) { throw "PowerShell 7 not found at '$PwshPath'." }
+    $Shell = $PwshPath
+}
+
+# Check VB365 is here before changing anything
+$moduleFile = Join-Path $env:ProgramFiles 'Veeam\Backup365\Veeam.Archiver.PowerShell\Veeam.Archiver.PowerShell.psd1'
+if (-not (Get-Module -ListAvailable -Name Veeam.Archiver.PowerShell) -and -not (Test-Path $moduleFile)) {
+    throw 'The Veeam Backup for Microsoft 365 PowerShell module (Veeam.Archiver.PowerShell) is not installed on this server.'
+}
+if (-not $Tenant -and $OrganizationTenants.Count -eq 0) {
+    Write-Warning 'No -Tenant or -OrganizationTenants: jobs will be listed under their Microsoft 365 organization name.'
+}
+
+if ($ApiUrl -notmatch '^https://') {
+    Write-Warning 'ApiUrl is not HTTPS: the API key would be sent in clear text.'
+}
+
+# Read the key as a SecureString so it isn't echoed to the console or kept in shell history
+$secure = Read-Host -AsSecureString 'API key (from: python manage.py create-key <name>)'
+$bstr = [Runtime.InteropServices.Marshal]::SecureStringToBSTR($secure)
+try { $apiKey = [Runtime.InteropServices.Marshal]::PtrToStringBSTR($bstr) }
+finally { [Runtime.InteropServices.Marshal]::ZeroFreeBSTR($bstr) }
+if (-not $apiKey.StartsWith('bdk_')) { throw "That doesn't look like a dashboard API key (expected 'bdk_...')." }
+
+# Config folder: SYSTEM + Administrators only (SIDs so this works on non-English Windows)
+New-Item -ItemType Directory -Path $DataDir -Force | Out-Null
+& icacls.exe $DataDir /inheritance:r /grant:r '*S-1-5-18:(OI)(CI)F' '*S-1-5-32-544:(OI)(CI)F' | Out-Null
+if ($LASTEXITCODE) { throw "icacls failed on $DataDir" }
+
+$config = [ordered]@{
+    ApiUrl              = $ApiUrl.TrimEnd('/')
+    ApiKey              = $apiKey
+    SourceSystem        = $SourceSystem
+    LookbackHours       = $LookbackHours
+    OrganizationTenants = $OrganizationTenants
+}
+if ($Tenant) { $config.Tenant = $Tenant }
+$config | ConvertTo-Json | Set-Content -Path $ConfigPath -Encoding UTF8
+
+New-Item -ItemType Directory -Path $InstallDir -Force | Out-Null
+$scriptPath = Join-Path $InstallDir 'Send-Vb365BackupStatus.ps1'
+Copy-Item -Path (Join-Path $PSScriptRoot 'Send-Vb365BackupStatus.ps1') -Destination $scriptPath -Force
+Unblock-File -Path $scriptPath
+
+$action = New-ScheduledTaskAction -Execute $Shell `
+    -Argument "-NoProfile -NonInteractive -ExecutionPolicy Bypass -File `"$scriptPath`""
+$trigger = New-ScheduledTaskTrigger -Once -At (Get-Date).AddMinutes(1) `
+    -RepetitionInterval (New-TimeSpan -Minutes $IntervalMinutes)
+$principal = New-ScheduledTaskPrincipal -UserId 'S-1-5-18' -LogonType ServiceAccount -RunLevel Highest
+$settings = New-ScheduledTaskSettingsSet -ExecutionTimeLimit (New-TimeSpan -Minutes 30) `
+    -MultipleInstances IgnoreNew -StartWhenAvailable
+Register-ScheduledTask -TaskName $TaskName -Action $action -Trigger $trigger -Principal $principal `
+    -Settings $settings -Description 'Sends Veeam Backup for Microsoft 365 results to the Backup Dashboard' -Force | Out-Null
+
+Write-Host "Installed. Config: $ConfigPath"
+Write-Host "Task '$TaskName' runs every $IntervalMinutes minutes as SYSTEM, using $Shell."
+Write-Host ''
+Write-Host 'Next steps:'
+Write-Host "  1. Preview what will be sent:   & '$Shell' -File '$scriptPath' -DryRun"
+Write-Host "  2. Backfill 30 days of history: & '$Shell' -File '$scriptPath' -LookbackHours 720"
+Write-Host "  3. Check the log:               Get-Content '$DataDir\vb365-collector.log' -Tail 20"
diff --git a/collectors/vb365/README.md b/collectors/vb365/README.md
new file mode 100644
index 0000000..f2dbbcd
--- /dev/null
+++ b/collectors/vb365/README.md
@@ -0,0 +1,85 @@
+# Veeam Backup for Microsoft 365 collector
+
+A PowerShell script that runs on the Veeam Backup for Microsoft 365 (VB365) server and reports its
+backup jobs (and backup copy jobs) to the dashboard, one dashboard job per VB365 job.
+
+> **Not yet checked against a real server.** The cmdlets are VB365's own (`Get-VBOJob`,
+> `Get-VBOJobSession`), but the properties of the objects they return aren't fully documented.
+> Before installing on the first server, run `Get-Vb365CollectorDiagnostics.ps1` and the collector
+> with `-DryRun` (see below) to confirm what it reads.
+
+## Which company a job appears under
+
+One VB365 server can protect several Microsoft 365 organizations, so the company is picked per job
+from the job's organization:
+
+1. `OrganizationTenants` maps an organization name (as `Get-VBOOrganization` shows it, e.g.
+   `acme.onmicrosoft.com`; not case-sensitive) to a dashboard company.
+2. Otherwise `Tenant`, for a VB365 server dedicated to one client.
+3. Otherwise the organization's own name.
+
+Changing a job's company later creates a new dashboard job under the new company; delete the old
+one with `python manage.py delete-job <id>`.
+
+## Install (on the VB365 server, as an administrator)
+
+1. On the dashboard host, create a key for this server:
+   ```bash
+   python manage.py create-key vb365-01
+   ```
+2. Copy this folder to the server and run one of:
+   ```powershell
+   # VB365 server for one client
+   .\Install-Vb365Collector.ps1 -ApiUrl https://backups.example.com -Tenant "Acme Corp"
+
+   # Shared VB365 server
+   .\Install-Vb365Collector.ps1 -ApiUrl https://backups.example.com -OrganizationTenants @{
+       'acme.onmicrosoft.com'      = 'Acme Corp'
+       'bluewater.onmicrosoft.com' = 'Bluewater Dental'
+   }
+   ```
+   It prompts for the key, then:
+   - writes `C:\ProgramData\BackupDashboard\vb365-collector.json` (readable only by SYSTEM and Administrators)
+   - copies the script to `C:\Program Files\BackupDashboard\`
+   - registers the scheduled task **Backup Dashboard - VB365 collector** (SYSTEM, every 60 minutes)
+
+   It runs under Windows PowerShell 5.1. If your VB365 version's module needs PowerShell 7, add
+   `-PwshPath 'C:\Program Files\PowerShell\7\pwsh.exe'`.
+3. Preview the payloads, then backfill 30 days so the history view is populated straight away:
+   ```powershell
+   powershell.exe -File 'C:\Program Files\BackupDashboard\Send-Vb365BackupStatus.ps1' -DryRun
+   powershell.exe -File 'C:\Program Files\BackupDashboard\Send-Vb365BackupStatus.ps1' -LookbackHours 720
+   ```
+
+It can be installed alongside the other collectors: it uses its own config, state, log and task.
+Re-run the installer to change settings (including the organization mapping) or update the script.
+
+## What it sends
+
+| Dashboard | VB365 |
+|---|---|
+| Company | See above |
+| Job | Each backup job and backup copy job. The job's GUID is the ID, so renaming it in VB365 doesn't duplicate it |
+| Status | Session status: Success / Warning / Failed. Running or queued → **Running**. Stopped (cancelled) or unrecognised → **Warning** |
+| Started / finished | Session `CreationTime` / `EndTime` |
+| Next scheduled | Job's `NextRun`. Empty for disabled jobs |
+| Message | Warning and error lines from the session log |
+| Size | Data transferred (`Statistics.TransferredData`) |
+| Details | Organization, objects processed, job kind (`backup` / `copy`) |
+
+Each run covers the last 48 hours (`LookbackHours`). Sessions already delivered are recorded in
+`vb365-collector.state.json`.
+
+## Troubleshooting
+
+- Log: `C:\ProgramData\BackupDashboard\vb365-collector.log`. Exit codes: `0` OK, `1` some jobs
+  failed to send (retried next run), `2` setup failed (config or VB365 module).
+- Wrong status, times or messages: run `.\Get-Vb365CollectorDiagnostics.ps1` (read-only). It prints
+  the real structure of jobs and sessions, including whether each date is local or UTC.
+
+## Testing without VB365
+
+```powershell
+. ./tests/MockVb365.ps1
+./Send-Vb365BackupStatus.ps1 -ConfigPath ./my-test-config.json -DryRun
+```
diff --git a/collectors/vb365/Send-Vb365BackupStatus.ps1 b/collectors/vb365/Send-Vb365BackupStatus.ps1
new file mode 100644
index 0000000..6140b52
--- /dev/null
+++ b/collectors/vb365/Send-Vb365BackupStatus.ps1
@@ -0,0 +1,354 @@
+<#
+.SYNOPSIS
+    Reports Veeam Backup for Microsoft 365 (VB365) job results to the Backup Dashboard.
+
+.DESCRIPTION
+    Runs on the VB365 server, normally as a SYSTEM scheduled task every 60 minutes
+    (see Install-Vb365Collector.ps1). For every backup job (and backup copy job) it sends:
+      - the job's next scheduled run, which drives the dashboard's Overdue flag, and
+      - every session from the last LookbackHours that the dashboard hasn't already received in
+        its final state. Running sessions are re-sent each time until they finish.
+
+    One VB365 server can protect several Microsoft 365 organizations, so the dashboard company is
+    chosen per job from its organization: OrganizationTenants in the config maps an organization
+    name (e.g. "contoso.onmicrosoft.com") to a company; otherwise Tenant is used; otherwise the
+    organization's own name.
+
+    Already-reported sessions are tracked in a state file, and the ingest API is idempotent, so a
+    failed or repeated run is harmless: anything not confirmed is retried next time.
+
+.PARAMETER ConfigPath
+    JSON config with ApiUrl and ApiKey (optional: Tenant, OrganizationTenants, SourceSystem,
+    LookbackHours).
+
+.PARAMETER LookbackHours
+    Overrides the config value. Use 720 once to backfill 30 days of history.
+
+.PARAMETER DryRun
+    Print the payloads instead of sending them. Doesn't touch the state or log files.
+
+.EXAMPLE
+    .\Send-Vb365BackupStatus.ps1 -DryRun
+.EXAMPLE
+    .\Send-Vb365BackupStatus.ps1 -LookbackHours 720
+#>
+[CmdletBinding()]
+param(
+    [string]$ConfigPath = (Join-Path $env:ProgramData 'BackupDashboard\vb365-collector.json'),
+    [int]$LookbackHours = 0,
+    [switch]$DryRun
+)
+
+$ErrorActionPreference = 'Stop'
+
+$DataDir = Split-Path -Parent $ConfigPath
+$LogPath = Join-Path $DataDir 'vb365-collector.log'
+$StatePath = Join-Path $DataDir 'vb365-collector.state.json'
+$MaxLogBytes = 5MB
+$Invariant = [Globalization.CultureInfo]::InvariantCulture
+
+# ---------- Helpers ----------
+
+function Write-Log {
+    param([string]$Message, [string]$Level = 'INFO')
+    $line = '{0} [{1}] {2}' -f (Get-Date).ToString('yyyy-MM-dd HH:mm:ss'), $Level, $Message
+    Write-Host $line
+    if ($DryRun) { return }
+    if ((Test-Path $LogPath) -and (Get-Item $LogPath).Length -gt $MaxLogBytes) {
+        Move-Item $LogPath "$LogPath.1" -Force
+    }
+    Add-Content -Path $LogPath -Value $line -Encoding UTF8
+}
+
+function Get-ErrorText($ErrorRecord) {
+    # Windows PowerShell puts the HTTP response body (e.g. the API's 422 explanation) here
+    if ($ErrorRecord.ErrorDetails -and $ErrorRecord.ErrorDetails.Message) {
+        return "$($ErrorRecord.Exception.Message) $($ErrorRecord.ErrorDetails.Message)"
+    }
+    return $ErrorRecord.Exception.Message
+}
+
+# The API needs an explicit UTC offset. DateTimeOffset keeps a Local/Unspecified time as local and a
+# Utc time as +00:00.
+function ConvertTo-IsoTime($Value) {
+    if ($null -eq $Value) { return $null }
+    $dt = [datetime]$Value
+    if ($dt.Year -le 1900) { return $null }  # "not set" (DateTime.MinValue and friends)
+    return ([DateTimeOffset]$dt).ToString("yyyy-MM-dd'T'HH:mm:sszzz", $Invariant)
+}
+
+# First property of $Object, out of $Names, that exists and isn't empty. The VB365 object model isn't
+# fully documented, so reads go through this rather than assuming one spelling.
+function Get-FirstValue($Object, [string[]]$Names) {
+    if ($null -eq $Object) { return $null }
+    foreach ($name in $Names) {
+        try {
+            $prop = $Object.PSObject.Properties[$name]
+            if (-not $prop) { continue }
+            $value = $prop.Value
+            # Check emptiness by type: casting to [string] would make a one-item list of objects ''
+            if ($null -eq $value) { continue }
+            if ($value -is [string] -and $value -eq '') { continue }
+            if ($value -is [Collections.ICollection] -and $value.Count -eq 0) { continue }
+            return $value
+        } catch { }
+    }
+    return $null
+}
+
+function Import-Vb365 {
+    if (Get-Command Get-VBOJob -ErrorAction SilentlyContinue) { return }  # already loaded
+    if (Get-Module -ListAvailable -Name Veeam.Archiver.PowerShell) {
+        Import-Module Veeam.Archiver.PowerShell
+        return
+    }
+    # Fall back to the default install path
+    Import-Module (Join-Path $env:ProgramFiles 'Veeam\Backup365\Veeam.Archiver.PowerShell\Veeam.Archiver.PowerShell.psd1')
+}
+
+function Get-Time($Object, [string]$Field) {
+    $value = Get-FirstValue $Object @($Field)
+    if ($null -eq $value) { return $null }
+    $dt = [datetime]$value
+    if ($dt.Year -le 1900) { return $null }  # e.g. EndTime while a session is running
+    return $dt
+}
+
+# "1.5 GB", "512 MB", "123456" -> bytes; $null when it can't be read
+function ConvertTo-Bytes($Value) {
+    if ($null -eq $Value) { return $null }
+    if ($Value -is [ValueType]) { return [long]$Value }
+    $match = [regex]::Match([string]$Value, '^\s*([\d.,]+)\s*([KMGTP]?B)?\s*$', 'IgnoreCase')
+    if (-not $match.Success) { return $null }
+    $number = 0.0
+    if (-not [double]::TryParse(($match.Groups[1].Value -replace ',', '.'), [Globalization.NumberStyles]::Float, $Invariant, [ref]$number)) {
+        return $null
+    }
+    $power = @{ '' = 0; 'B' = 0; 'KB' = 1; 'MB' = 2; 'GB' = 3; 'TB' = 4; 'PB' = 5 }[$match.Groups[2].Value.ToUpperInvariant()]
+    return [long]($number * [math]::Pow(1024, $power))
+}
+
+# ---------- Jobs and tenants ----------
+
+function Get-OrganizationName($Job) {
+    $org = Get-FirstValue $Job @('Organization')
+    if ($null -eq $org) {
+        # Copy jobs point at their source backup job
+        $org = Get-FirstValue (Get-FirstValue $Job @('BackupJob')) @('Organization')
+    }
+    if ($org -is [string]) { return $org }
+    $name = Get-FirstValue $org @('Name', 'OfficeName', 'DisplayName')
+    if ($name) { return [string]$name }
+    return $null
+}
+
+function Get-TenantForJob($Job) {
+    $org = Get-OrganizationName $Job
+    if ($org -and $Config.OrganizationTenants) {
+        $mapped = $Config.OrganizationTenants.PSObject.Properties[$org]  # case-insensitive lookup
+        if ($mapped -and $mapped.Value) { return [string]$mapped.Value }
+    }
+    if ($Config.Tenant) { return [string]$Config.Tenant }
+    if ($org) { return $org }
+    return $env:COMPUTERNAME
+}
+
+function Get-NextRun($Job) {
+    try {
+        $enabled = Get-FirstValue $Job @('IsEnabled', 'Enabled')
+        if ($enabled -eq $false) { return $null }
+        return ConvertTo-IsoTime (Get-Time $Job 'NextRun')
+    } catch {
+        Write-Log "Couldn't read schedule for job '$($Job.Name)': $(Get-ErrorText $_)" 'WARN'
+        return $null
+    }
+}
+
+# ---------- Sessions ----------
+
+function Get-RunStatus($Session) {
+    $status = [string](Get-FirstValue $Session @('Status', 'Result', 'State'))
+    if ($status -match 'Fail|Error') { return 'failed' }
+    if ($status -match 'Warn') { return 'warning' }
+    if ($status -match 'Succe') { return 'success' }
+    if ($status -match 'Run|Queue|Progress|Start|Wait') { return 'running' }
+    if (-not (Get-Time $Session 'EndTime')) { return 'running' }
+    # Stopped (cancelled), Disconnected, or a state we don't recognise: surface it rather than hide it
+    return 'warning'
+}
+
+# Warning/error lines from the session log
+function Get-RunMessage($Session, [string]$Status) {
+    if ($Status -eq 'running') { return '' }
+    $lines = New-Object 'System.Collections.Generic.List[string]'
+    $sessionStatus = [string](Get-FirstValue $Session @('Status', 'Result', 'State'))
+    if ($Status -ne 'success') {
+        foreach ($entry in @(Get-FirstValue $Session @('Log', 'Logs') | Where-Object { $_ })) {
+            $title = [string](Get-FirstValue $entry @('Title', 'Message', 'Text'))
+            $entryText = "$title $([string](Get-FirstValue $entry @('Status', 'Type', 'Severity')))"
+            if ($title -and $entryText -match 'Warn|Fail|Error') {
+                $title = $title.Trim()
+                if (-not $lines.Contains($title)) { $lines.Add($title) }
+            }
+        }
+    }
+    if ($lines.Count -eq 0) {
+        if ($Status -eq 'success') { return 'Job completed successfully.' }
+        return "Job finished with status '$sessionStatus'."
+    }
+    if ($sessionStatus -and $sessionStatus -notmatch 'Fail|Warn') { $lines.Insert(0, "Session status: $sessionStatus") }
+    return ($lines -join "`n")
+}
+
+function ConvertTo-Run($Session, $Job, [string]$JobKind) {
+    $status = Get-RunStatus $Session
+    $details = [ordered]@{ vb365_server = $env:COMPUTERNAME; job_kind = $JobKind }
+    $org = Get-OrganizationName $Job
+    if ($org) { $details.organization = $org }
+    $sessionStatus = Get-FirstValue $Session @('Status', 'Result', 'State')
+    if ($sessionStatus) { $details.vb365_status = [string]$sessionStatus }
+
+    $run = [ordered]@{
+        external_id = [string](Get-FirstValue $Session @('Id', 'SessionId'))
+        status      = $status
+        started_at  = ConvertTo-IsoTime (Get-Time $Session 'CreationTime')
+        message     = Get-RunMessage $Session $status
+        details     = $details
+    }
+    if ($status -ne 'running') {
+        $finished = ConvertTo-IsoTime (Get-Time $Session 'EndTime')
+        if ($finished) { $run.finished_at = $finished }  # otherwise the API uses receipt time
+        $stats = Get-FirstValue $Session @('Statistics')
+        $processed = Get-FirstValue $stats @('ProcessedObjects')
+        if ($null -ne $processed) { $details.processed_objects = $processed }
+        $transferred = ConvertTo-Bytes (Get-FirstValue $stats @('TransferredData', 'TransferredDataSize'))
+        if ($transferred -gt 0) { $run.size_bytes = $transferred }
+    }
+    return $run
+}
+
+function Send-Report($Body) {
+    $json = $Body | ConvertTo-Json -Depth 6 -Compress
+    if ($DryRun) {
+        Write-Host $json
+        return
+    }
+    # Send bytes: Windows PowerShell would otherwise encode a string body as Latin-1
+    $params = @{
+        Uri         = "$($Config.ApiUrl.TrimEnd('/'))/api/v1/ingest"
+        Method      = 'Post'
+        Headers     = @{ Authorization = "Bearer $($Config.ApiKey)" }
+        ContentType = 'application/json; charset=utf-8'
+        Body        = [Text.Encoding]::UTF8.GetBytes($json)
+        TimeoutSec  = 30
+    }
+    Invoke-RestMethod @params | Out-Null
+}
+
+# ---------- Main ----------
+
+try {
+    $Config = Get-Content -Path $ConfigPath -Raw | ConvertFrom-Json
+    foreach ($key in 'ApiUrl', 'ApiKey') {
+        if (-not $Config.$key) { throw "Config $ConfigPath is missing '$key'" }
+    }
+    $SourceSystem = if ($Config.SourceSystem) { [string]$Config.SourceSystem } else { 'Veeam Backup for M365' }
+    if ($LookbackHours -le 0) {
+        $LookbackHours = if ($Config.LookbackHours) { [int]$Config.LookbackHours } else { 48 }
+    }
+
+    # Windows PowerShell 5.1 may default to TLS 1.0
+    [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12
+
+    Import-Vb365
+
+    # Session ID -> start time (Unix seconds), for sessions already delivered in their final state
+    $sent = @{}
+    if (Test-Path $StatePath) {
+        $saved = Get-Content -Path $StatePath -Raw | ConvertFrom-Json
+        if ($saved) { foreach ($p in $saved.PSObject.Properties) { $sent[$p.Name] = [long]$p.Value } }
+    }
+
+    $since = (Get-Date).AddHours(-$LookbackHours)
+
+    # (job, kind, sessions) for backup jobs, plus backup copy jobs where the cmdlets exist
+    $work = New-Object 'System.Collections.Generic.List[object]'
+    foreach ($job in @(Get-VBOJob)) {
+        $sessions = @(Get-VBOJobSession -Job $job | Where-Object { (Get-Time $_ 'CreationTime') -ge $since })
+        $work.Add([pscustomobject]@{ Job = $job; Kind = 'backup'; Sessions = $sessions })
+    }
+    if ((Get-Command Get-VBOCopyJob -ErrorAction SilentlyContinue) -and (Get-Command Get-VBOCopyJobSession -ErrorAction SilentlyContinue)) {
+        $copyJobs = @(Get-VBOCopyJob)
+        if ($copyJobs.Count) {
+            # Fetch once and match by job ID, since the per-job parameter name isn't consistent
+            $copySessions = @(Get-VBOCopyJobSession | Where-Object { (Get-Time $_ 'CreationTime') -ge $since })
+            foreach ($job in $copyJobs) {
+                $id = [string]$job.Id
+                $work.Add([pscustomobject]@{
+                    Job = $job; Kind = 'copy'
+                    Sessions = @($copySessions | Where-Object { [string](Get-FirstValue $_ @('JobId')) -eq $id })
+                })
+            }
+        }
+    }
+} catch {
+    Write-Log "Collector setup failed: $(Get-ErrorText $_)" 'ERROR'
+    exit 2
+}
+
+$failures = 0
+$runsSent = 0
+foreach ($item in $work) {
+    $job = $item.Job
+    $tenant = Get-TenantForJob $job
+    $jobInfo = [ordered]@{
+        external_id = [string]$job.Id
+        name        = [string]$job.Name
+        # Always sent (null when disabled/unscheduled) so the dashboard's value tracks VB365's
+        next_run_at = Get-NextRun $job
+    }
+    $pending = @($item.Sessions |
+        Where-Object { $_ -and -not $sent.ContainsKey([string](Get-FirstValue $_ @('Id', 'SessionId'))) } |
+        Sort-Object { Get-Time $_ 'CreationTime' })
+
+    try {
+        if ($pending.Count -eq 0) {
+            # Keep next_run_at fresh even when nothing new ran
+            Send-Report ([ordered]@{ tenant = $tenant; source_system = $SourceSystem; job = $jobInfo })
+        }
+        foreach ($session in $pending) {
+            $run = ConvertTo-Run $session $job $item.Kind
+            Send-Report ([ordered]@{ tenant = $tenant; source_system = $SourceSystem; job = $jobInfo; run = $run })
+            $runsSent++
+            if ($run.status -ne 'running') {
+                $sent[$run.external_id] = ([DateTimeOffset](Get-Time $session 'CreationTime')).ToUnixTimeSeconds()
+            }
+        }
+    } catch {
+        $failures++
+        Write-Log "Failed to report job '$($job.Name)': $(Get-ErrorText $_)" 'ERROR'
+        $httpStatus = 0
+        try { $httpStatus = [int]$_.Exception.Response.StatusCode } catch { }
+        if ($httpStatus -eq 401) {
+            Write-Log 'API key rejected; check ApiKey in the config. Stopping.' 'ERROR'
+            break
+        }
+    }
+}
+
+if (-not $DryRun) {
+    # Forget sessions that have aged out of the lookback window (plus a day of slack)
+    $cutoff = [DateTimeOffset]::Now.AddHours(-$LookbackHours - 24).ToUnixTimeSeconds()
+    $keep = [ordered]@{}
+    foreach ($id in $sent.Keys) {
+        if ($sent[$id] -ge $cutoff) { $keep[$id] = $sent[$id] }
+    }
+    try {
+        $keep | ConvertTo-Json -Compress | Set-Content -Path $StatePath -Encoding UTF8
+    } catch {
+        Write-Log "Couldn't save state file: $(Get-ErrorText $_)" 'WARN'
+    }
+}
+
+Write-Log ("Reported {0} jobs, {1} runs, {2} failures" -f $work.Count, $runsSent, $failures)
+if ($failures) { exit 1 }
diff --git a/collectors/vb365/tests/MockVb365.ps1 b/collectors/vb365/tests/MockVb365.ps1
new file mode 100644
index 0000000..e95f2d6
--- /dev/null
+++ b/collectors/vb365/tests/MockVb365.ps1
@@ -0,0 +1,71 @@
+# Stand-ins for the Veeam Backup for Microsoft 365 cmdlets. Object shapes are best guesses until
+# checked against Get-Vb365CollectorDiagnostics.ps1 output from a real server.
+#
+#   . ./tests/MockVb365.ps1
+#   ./Send-Vb365BackupStatus.ps1 -ConfigPath ./my-test-config.json -DryRun
+
+# Fixed to the top of the hour, and IDs derived from names/times, so repeated runs see the same data
+$now = Get-Date -Minute 0 -Second 0 -Millisecond 0
+function New-StableGuid([string]$Seed) {
+    [guid]::new([Security.Cryptography.MD5]::Create().ComputeHash([Text.Encoding]::UTF8.GetBytes($Seed)))
+}
+
+$acme = [pscustomobject]@{ Name = 'acme.onmicrosoft.com'; Type = 'Office365' }
+$blue = [pscustomobject]@{ Name = 'bluewater.onmicrosoft.com'; Type = 'Office365' }
+
+function New-MockJob($Name, $Org, $NextRun, [bool]$Enabled = $true) {
+    [pscustomobject]@{
+        Id = New-StableGuid $Name; Name = $Name; Organization = $Org
+        IsEnabled = $Enabled; NextRun = $NextRun; LastStatus = 'Success'
+    }
+}
+
+function New-MockSession($Job, $Start, $End, $Status, $Transferred = '0 B', [int]$Objects = 0, $Log = @()) {
+    [pscustomobject]@{
+        Id = New-StableGuid "$($Job.Name)|$($Start.Ticks)"; JobId = $Job.Id; JobName = $Job.Name
+        CreationTime = $Start; EndTime = $(if ($End) { $End } else { [datetime]::MinValue })
+        Status = $Status
+        Statistics = [pscustomobject]@{ ProcessedObjects = $Objects; TransferredData = $Transferred }
+        Log = $Log
+    }
+}
+
+function New-LogEntry($Title, $Status = 'Success') { [pscustomobject]@{ Title = $Title; Status = $Status } }
+
+$global:MockVboJobs = @(
+    (New-MockJob 'Acme - Exchange & OneDrive' $acme $now.AddHours(3)),
+    (New-MockJob 'Acme - SharePoint & Teams' $acme $now.AddHours(5)),
+    (New-MockJob 'Bluewater - Full Org' $blue $now.AddMinutes(30)),
+    (New-MockJob 'Bluewater - Old Mailboxes' $blue $now.AddDays(1) $false)  # disabled
+)
+$exo, $spo, $bw, $old = $global:MockVboJobs
+
+$global:MockVboSessions = @(
+    (New-MockSession $exo $now.AddHours(-21) $now.AddHours(-20.5) 'Success' '1.5 GB' 412 @(
+        (New-LogEntry 'Processing mailbox jsmith@acme.com'), (New-LogEntry 'Job finished'))),
+    (New-MockSession $exo $now.AddHours(-1) $null 'Running' '0 B' 10),
+    (New-MockSession $spo $now.AddHours(-19) $now.AddHours(-18) 'Warning' '512 MB' 38 @(
+        (New-LogEntry 'Processing site Marketing'),
+        (New-LogEntry 'Item "Budget 2026.xlsx" was skipped: file is locked' 'Warning'))),
+    (New-MockSession $bw $now.AddHours(-6) $now.AddHours(-5.9) 'Failed' '0 B' 0 @(
+        (New-LogEntry 'Failed to connect to Exchange Online: (401) Unauthorized' 'Failed'))),
+    (New-MockSession $bw $now.AddHours(-30) $now.AddHours(-29.5) 'Stopped' '2 GB' 120),  # cancelled
+    (New-MockSession $old $now.AddDays(-5) $now.AddDays(-5).AddHours(1) 'Success')  # outside 48h lookback
+)
+
+# A backup copy job (to object storage) for Acme's mailbox job
+$global:MockVboCopyJobs = @(
+    [pscustomobject]@{ Id = New-StableGuid 'acme-copy'; Name = 'Acme - Exchange copy to Wasabi'; BackupJob = $exo; IsEnabled = $true; NextRun = $null }
+)
+$global:MockVboCopySessions = @(
+    [pscustomobject]@{
+        Id = New-StableGuid 'acme-copy-s1'; JobId = $global:MockVboCopyJobs[0].Id; CreationTime = $now.AddHours(-20); EndTime = $now.AddHours(-19.8)
+        Status = 'Success'; Statistics = [pscustomobject]@{ ProcessedObjects = 412; TransferredData = '1.4 GB' }; Log = @()
+    }
+)
+
+function Get-VBOJob { $global:MockVboJobs }
+function Get-VBOJobSession { param($Job) $global:MockVboSessions | Where-Object { -not $Job -or $_.JobId -eq $Job.Id } }
+function Get-VBOOrganization { $acme, $blue }
+function Get-VBOCopyJob { $global:MockVboCopyJobs }
+function Get-VBOCopyJobSession { $global:MockVboCopySessions }