(auth failed, 1 attempts in 180 secs)
It means the authentication process fails. Your mail application uses wrong username and/or password. It could happen if you specify wrong mail username, password, encryption mechanism, etc.
Currently I recommend you to make sure you use full mailbox name (e.g. address@domain.com) as the mail username and correct password for the mailbox (the login and password are case sensitive).
Additionally, you can find the correct mail settings in the user panel under "Email accounts" --> "Email accounts".
I know he's set the password correctly, the user, I don't know if he's set it completely or not (user@domain.com), I'll tell him to try it.
Indeed, the error he indicates is authentication failure but... he's already configured other accounts in the past, I'm very surprised that he doesn't know how to configure these...
The configuration that appears in user accounts is for "Windows live mail configuration" and I don't know if it would be valid for a Mac...
(I'm quite unfamiliar with the Mac world... I only know that he uses the native Mac application for mail and that his Mac is less than a year old, so it's relatively new).
Sounds like the mac might be using an incompatible encryption algorithm.
It's just what I thought, an incompatible encryption algorithm.
Why? In the past, when I was using an older Mac I had to change the server's "crypto-policies" to:
update-crypto-policies --set LEGACY
But that was with an older Mac.
Now I'm using a newer one, I've tried setting it to LEGACY or Default, still having the same problem...
But what algorithm does that Mac use? How to fix it on the server?
That's the question...
Thanks to both of you for your answers.