Powershell Try catch write errors to an external txt file - powershell

Question

I have a PowerShell script to disable email forwarding in Office 365 using a CSV file. I want to catch all errors to an external Txt file.
Here's my code:
$Groups |
ForEach-Object {
$PrimarySmtpAddress = $_.PrimarySmtpAddress
try {
# disable Mail forwarding
Set-Mailbox -Identity $PrimarySmtpAddress -ForwardingSmtpAddress $Null
}
Catch {
$PrimarySmtpAddress | Out-File $logfile -Append
}
}
but it doesn't catch errors.
Is there any instruction to catch errors to an external file?
Any solution will be helpful.

Answer 1

From Jeff Zeitlin's and TheMadTechnician's comments, changes noted in inline comments:
$Groups | ForEach-Object {
$PrimarySmtpAddress = $_.PrimarySmtpAddress
Try {
# disable Mail forwarding
#Added ErrorAction Stop to cause errors to be terminating
Set-Mailbox -Identity $PrimarySmtpAddress -ForwardingSmtpAddress $Null -ErrorAction Stop
}
Catch {
#Removed Write-Host as Write-Host writes to the host, not down the pipeline, Write-Output would also work
"$PrimarySmtpAddress" | Out-File $logfile -Append
}
}

Answer 2

Try this:
$ErrorMessage = $_.Exception.Message
#or $ErrorMessage= $Error[0].Exception.Message
if($ErrorMessage -ne $null) {
... Your custom code
}

Answer 3

Exchange Online (a.k.a O365) does not honor the thrown error for your catch statement to work. We have had to set
$global:ErrorActionPreference=Stop
to get the error object to return
Note: We implemented this using the following at beginning of function
$saved=$global:ErrorActionPreference
$global:ErrorActionPreference=Stop
and reverted the setting at the end of the function using
$global:ErrorActionPreference=$saved