johnny
Below is what I found in the logs.
helpdesk@getmydomain.com is setup as the IMAP.
noreply@getmydomain.com is setup as the SMTP.
It looks like the SMTP credentials is trying to send on behalf of the IMAP credentials.
[Fri Aug 18 16:57:33.382965 2023] [php:notice] [pid 1489] [client 172.58.123.27:49130] ITFlow - Failed to send email: SMTP Error: data not accepted.SMTP server error: DATA END command failed Detail: 5.2.252 SendAsDenied; noreply@getmydomain..com not allowed to send as helpdesk@getmydomain.com; STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message [BeginDiagnosticData]Cannot submit message. 0.35250:7C320000, 1.36674:0A000000, 1.61250:00000000, 1.45378:02000000, 1.44866:6E200000, 1.36674:0E000000, 1.61250:00000000, 1.45378:73200000, 1.44866:6C010000, 16.55847:5F110000, 17.43559:0000000024020000000000000000 SMTP code: 554, referer: https://itflow.getmydomain.com/client_documents.php?client_id=2&folder_id=24
[Fri Aug 18 16:57:33.423658 2023] [php:warn] [pid 1489] [client 172.58.123.27:49130] PHP Warning: Undefined variable $item_mail in /var/www/itflow.getmydomain.com/ajax.php on line 294, referer: https://itflow.getmydomain.com/client_documents.php?client_id=2&folder_id=24