Office 365: Release Messages from Quarantine using PowerShell

$DomainFilter = "@mydomain\.com$"
$totalPages = 10
$pageSize = 1000

Connect-ExchangeOnline

Write-Host "Fetching up to $($totalPages * $pageSize) pending quarantine messages across $totalPages pages..." -ForegroundColor Cyan

# Efficiently gather multiple pages of results
$allQuarantinedMessages = foreach ($page in 1..$totalPages) {
    Write-Host "Fetching page $page..." -ForegroundColor DarkCyan
    
    $pageResults = Get-QuarantineMessage -PageSize $pageSize -Page $page
    
    # If a page returns nothing, we've hit the end of the queue. Break the loop early.
    if (-not $pageResults) {
        Write-Host "Reached the end of the queue before page $totalPages." -ForegroundColor DarkGray
        break
    }
    
    # Output the results to the $allQuarantinedMessages collection
    $pageResults
}

# Filter the combined results for internal-to-internal routing waiting for review
$filteredMessages = $allQuarantinedMessages | Where-Object {
    $_.SenderAddress -match $DomainFilter -and 
    $_.RecipientAddress -match $DomainFilter -and
    $_.ReleaseStatus -eq "NotReleased"
}

if ($filteredMessages) {
    
    # Pipe the filtered results to an interactive grid view for selection
    $selectedMessages = $filteredMessages | 
        Select-Object ReceivedTime, SenderAddress, RecipientAddress, Subject, ReleaseStatus, Identity | 
        Out-GridView -Title "Select Pending Messages to Release (Hold CTRL to select multiple)" -PassThru
    
    # Process the selected messages
    if ($selectedMessages) {
        
        # Filter down to distinct IDs to avoid duplicate release attempts on CC'd messages
        $uniqueMessages = $selectedMessages | Sort-Object Identity -Unique

        foreach ($msg in $uniqueMessages) {
            Write-Host "Releasing message: '$($msg.Subject)' (Message ID: $($msg.Identity))" -ForegroundColor Yellow
            
            # Release the message to all originally intended recipients
            Release-QuarantineMessage -Identity $msg.Identity -ReleaseToAll
        }
        Write-Host "Release process complete." -ForegroundColor Green
    } else {
        Write-Host "No messages were selected. Exiting." -ForegroundColor DarkGray
    }

} else {
    Write-Host "No pending quarantined messages found matching the @levian.com criteria in the first $totalPages pages." -ForegroundColor Red
}