I have OSTicket running on an Ubuntu server version 24.04.1 LTS. The OST is version 1.17.5 with Apache 2.4.58, MySQL 10.11.8, and PHP 8.0.30. I have the Oauth2 plugin version 0.6 installed and everything has been working well. Then on January 30 mail suddenly stopped flowing. I've made no changes to my OST config and I have made no changes to the O365 tenant through which I handle IMAP and SMTP. Not entirely sure what might have happened and as a result, I'd really appreciate a hand. The error I receive when trying to send mail (either in the normal course or by using the diagnostic sending tool on the dashboard) is:
Mailer Error
Unable to email via Sendmail Unable to send mail: Unknown error
Not sure if this will be helpful information, but I noticed that the IP address for the log entry is the gateway (but I presume that is because I am logged into the SCP, but please correct me if I'm wrong). FWIW I also have made no changes to the local network. In fact I still see calls from my OST server's IP to Microsoft Authentication in my firewall logs the same as I saw them before January 30.
What am I doing wrong? Thanks in advance!