Integrating Nextcloud with a third-party full service email provider

I am a happy Nextcloud user and have been for a number of years. I am on 27.0.1 and my use case has been for files and notes up to now. Sharing between 3 family members.
I have been thinking about broadening my useage to include Talk, Calendar, email and so on but I have com across a situation recently which prevents this. Each of the email accounts I set up for my family members works just fine from Thunderbird, Webmail, and so on but the Mail configuration dialog for Nextcloud always returns the error “IMAP username or password is wrong” even if the credential are verifiably correct.
This is true not only for setting up Mail but also for Snappymail.
I am thinking it is some kind of glitch in the URL validation.

The format of the full service email server for a full service user to use during their setup is the email of the user to be with the imap server called out as (note the two hyphens!) and (again 2 hyphens!). Of course there are the usual ports and SSL selections too.

Other standalone email clients don’t seem to have a problem with these server strings and hyphen is permitted as a spacer but Nextcloud cannot somehow digest them! I suspect that others may want these full service email accounts to avoid the nightmares of self hosting.

Mail seems to be a dependency for these other Nextcloud services I would like to take advantage of and the risks and effort of hosting my own server are quite high so a full service email seemed like a good idea.
Has anyone seen this phenomenon before. Is this a bug or am I missing something?
Thanks in advance for any advice. Is there a configuration file somewhere I can poke around in?

Hi @brinycoolie - Sorry you didn’t get a response to this. Not sure why. I’ve moved it into the section specifically for the Mail app. In any case, I don’t know why you would have had authentication issues. That’s… Odd.

There is additional debug logging that can be turned on and some other troubleshooting tidbits. They can be found here: