Why am I getting authentication errors when connecting to a custom email account?

[Liam Sanderson]

The error we're getting is that Jira cannot connect to the mail server. We had this issue last week and that was due to an expired password on the custom email address, so I updated the password and that seemed to solve the issue, however the issue has re-appeared. 

Can anyone assist please?

[Nic Brough -Adaptavist-]

Either someone has changed the password again, or the email server has been (re)configured to reject your account for some reason.