Goes through CSV and unhides users in Exchange Online

UnHideUsersFromGAL.ps1

<# ------------------------------------------------------------
 UnhideFromGAL_FromExport_WithStatusCsv.ps1

 Uses the export CSV from the proxy export (Identity,Type,Value).
 Processes UNIQUE identities and sets:
   HiddenFromAddressListsEnabled = $false

 Writes a status CSV in the same format as the import CSV log:
   Identity,Type,Value,Status,Message,Timestamp

 Hard-coded paths.
 Supports -WhatIf / -Confirm via ShouldProcess.

 Notes:
 - This will only "unhide" (set to false). It will not hide anyone.
 - Requires Get-Mailbox / Set-Mailbox rights.
------------------------------------------------------------- #>

[CmdletBinding(SupportsShouldProcess = $true, ConfirmImpact = 'Medium')]
param()

# ----------------------------
# Hard-coded settings
# ----------------------------
$InputCsv  = "C:\Data\UnhideGAL.csv"
$StatusCsv = "C:\Data\UnhideGAL_Status_{0}.csv" -f (Get-Date -Format "yyyyMMdd_HHmmss")

# If your CSV is semicolon-delimited, set this to ';' otherwise ','
$Delimiter = ','

# ----------------------------
# Helpers
# ----------------------------
function New-StatusRow {
    param(
        [string]$Identity,
        [string]$Type,
        [string]$Value,
        [string]$Status,
        [string]$Message
    )
    [pscustomobject]@{
        Identity  = $Identity
        Type      = $Type
        Value     = $Value
        Status    = $Status
        Message   = $Message
        Timestamp = (Get-Date -Format "yyyy-MM-dd HH:mm:ss")
    }
}

Write-Host "Reading identities from: $InputCsv" -ForegroundColor Cyan
Write-Host "Writing status CSV to: $StatusCsv" -ForegroundColor Cyan

if (-not (Test-Path $InputCsv)) {
    throw "Input CSV not found: $InputCsv"
}

# Import export file
$rows = Import-Csv -Path $InputCsv -Delimiter $Delimiter
if (-not $rows -or $rows.Count -eq 0) {
    throw "No rows found in CSV: $InputCsv"
}

# Validate required column exists
$cols = $rows[0].PSObject.Properties.Name
if ($cols -notcontains "Identity") {
    throw "CSV must contain column 'Identity'. Found: $($cols -join ', ')"
}

# Build a unique list of identities, while keeping a representative Type/Value for logging format
$identityMap = @{}  # Identity -> @{Type=; Value=}
foreach ($r in $rows) {
    $id = ([string]$r.Identity).Trim()
    if ([string]::IsNullOrWhiteSpace($id)) { continue }

    if (-not $identityMap.ContainsKey($id)) {
        # Keep first seen Type/Value (if present) just for log shape
        $t = ""
        $v = ""
        if ($cols -contains "Type")  { $t = ([string]$r.Type).Trim() }
        if ($cols -contains "Value") { $v = [string]$r.Value }
        $identityMap[$id] = @{ Type = $t; Value = $v }
    }
}

$statusOut = New-Object System.Collections.Generic.List[object]

if ($identityMap.Keys.Count -eq 0) {
    $statusOut.Add((New-StatusRow -Identity "" -Type "" -Value "" -Status "Error" -Message "No valid Identity values found in CSV"))
    $statusOut | Export-Csv -Path $StatusCsv -NoTypeInformation -Encoding UTF8
    throw "No valid Identity values found in CSV."
}

foreach ($id in ($identityMap.Keys | Sort-Object)) {

    $t = $identityMap[$id].Type
    $v = $identityMap[$id].Value

    try {
        # Get mailbox
        $mbx = Get-Mailbox -Identity $id -ErrorAction Stop

        # If already unhidden, record and skip
        if ($mbx.HiddenFromAddressListsEnabled -eq $false) {
            $statusOut.Add((New-StatusRow -Identity $id -Type $t -Value $v -Status "SkippedAlreadyUnhidden" -Message "HiddenFromAddressListsEnabled is already False"))
            continue
        }

        if ($PSCmdlet.ShouldProcess($id, "Set HiddenFromAddressListsEnabled to False (Unhide from GAL)")) {
            Set-Mailbox -Identity $id -HiddenFromAddressListsEnabled $false -ErrorAction Stop
            $statusOut.Add((New-StatusRow -Identity $id -Type $t -Value $v -Status "Updated" -Message "Mailbox unhidden from GAL (HiddenFromAddressListsEnabled=False)"))
        }
        else {
            $statusOut.Add((New-StatusRow -Identity $id -Type $t -Value $v -Status "WhatIf" -Message "Would unhide mailbox from GAL"))
        }
    }
    catch {
        $statusOut.Add((New-StatusRow -Identity $id -Type $t -Value $v -Status "Error" -Message $_.Exception.Message))
        continue
    }
}

$statusOut | Export-Csv -Path $StatusCsv -NoTypeInformation -Encoding UTF8
Write-Host "Done. Status written to: $StatusCsv" -ForegroundColor Green