Some users can not update their settings

I have an user who can not update his email settings,
when he change the settings, and save, after coming back the old settings are back.
Both for imap and smtp.
The problem is that his password changed on the mail server, so they have no access to mail anymore.
I do not know how to solve the issue, as I was able to change it for another user.

I fixed it, there was a pb on the smtp server side who refused to authenticate
so the settings were not updated.
Maybe it could be nice to split the imap and smtp part, at least the user could have been able to read his mails, while the smtp was broken.