No outgoing emails on tickets

We get no emails returned to the customer side of the tickets. I have custom SMTP set up with forwarding set up. It was working before but today I get nothing. I even took out the custom settings for email and it still has nothing outgoing. I do however get tickets updated from the customer sided when adding a comment or attachment. Is there something I'm missing.

It's a problem with our SMTP settings somewhere. It works for a day then stops working with an Authentication problem. We had to revert back to using the plumsail address to send the emails.

Hello! Could you try to set-up the custom SMTP again and test it? If the issue is reproduced, please provide me with HelpDesk instance URL where the issue occurred, approximate time periods (+ time-zone) when it worked and when it stopped working, and if possible a sample ticket ID for which notifications were not sent. You can share the information either through private messages here, in the community, or raise a ticket by sending a message to support@plumsail.com. In the latter case, please refer to this topic.