Email usernames seem case sensitive. Error "Cannot send mail as" whenever the text case doesn't match.

[d19dotca]

Hello,

Recently ran into an odd one to me, mostly because I understood from various specs that emails should be case insensitive, but it seems this may conflict with Cloudron authentication which I guess is case sensitive?

A client recently setup their Mail client app after a rebuild, and while I always encourage my clients to use all lowercase for their usernames as a best practice, they used Michelle@example.com for their username instead of michelle@example.com. Received the following error in the logs when she tried to send:

Jun 14 09:54:23 [INFO] [84E9F590-D0B1-4CB6-8F29-053BB08D3EEF.1] [core] hook=mail plugin=cloudron function=authorize_mail_from params=<michelle@example.com> retval=DENY msg="Authenticated user Michelle@example.com cannot send mail as michelle@example.com"

My concerns are the following:

1. Usernames and email addresses should be case insensitive. Is Cloudron case-sensitive when it comes to usernames?
2. If usernames were case sensitive (which seems to be the case here), then why is it even authenticating Michelle@ in the first place when the mailbox name is established in Cloudron as michelle@?

My expectations:

1. User logs in as Michelle@example.com or even MICHELLE@example.com which Cloudron should equate as michelle@example.com
2. User able to send mail as anything that matches their username email, since case sensitivity should not matter.

[girish]

@d19dotca We have tests to make sure that mailbox delivery code is case insensitive. But maybe there is a bug that authentication username is case sensitive.

[d19dotca]

@girish Yes, definitely seems like a defect somewhere. I initially didn't think it was related to that case sensitivity and had even informed my clients before that they're not case-sensitive, but this seems to either not be the case any longer (changed inadvertently?) or I just perhaps never ran into it before but it maybe was case sensitive for a while now, not too sure. Hopefully this can be fixed though, as this will certainly present more issues as the business grows too and more clients are onboarded.

[girish]

I managed to reproduce it:

[girish]

Indeed, there was a missing normalization. I have fixed it for the next release.