[Bug] - Apple Mail periodically fails connection

[alicethefemme]

From Support Helpdesk, multiple users have experienced issues with Apple Mail (Desktop and Mobile), periodically failing the authentication, for no determinable reason. All evidence points to everything being valid, with no server events suggesting that this even occurred. Need to test at some point what is occurring, and what needs changing either side to allow proper authentication.

[boogah]

From what I can see, if the setting "Automatically manage connection settings" is checked for the SMTP server settings in Mail.app, it attempts to use port 25 and throws up errors.

Unchecking that, manually changing the port to 465 and checking "Use TLS/SSL" seems to allow me to send again. Mail.app doesn't always want to hold onto this setting, but going back in and changing it fixes me back up.

Oh, using macOS 26.1 (regrettably) if that helps.