Support scope clarification
We’re getting a few support queries at the moment relating to mail server authentication problems. To be clear, Jira is responsible for definition of mail hosts and connectivity to those hosts, when a mail has been successfully retrieved, then JEMH is invoked (by Jira), and our support scope begins. We try to be helpful, and offer suggestions - our support is best effort as this problem area is not in our support scope. Problems with the Jira platform should be directed to support.atlassian.com
Below are some current references on authentication impacting changes (removal of basic auth)
O365 (affects POP/IMAP)
When will this change take place?
We've already started making this change. New Microsoft 365 tenants are created with Basic authentication already turned off as they have Security defaults enabled.
So effectively 1 OCT 2022 basic auth will start to be disabled regardless of usage, SMTP basic auth remains valid.
See related update: https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-and-exchange-online-september-2021-update/ba-p/2772210
Authentication problems?
If you are unable to authenticate, maybe this can help.
Gmail (affects POP/IMAP)
Quoting:
You may need to enable 2SV: https://support.google.com/a/answer/9176657 and then use the app password instead of your regular password: https://support.google.com/accounts/answer/185833 .