How to login to IMAP client using custom domain mail?

Question

I recently moved from outlook to icloud-mail (as it's free) using my custom domain. Switching was easy, now I'm trying to move my existing mails from outlook to icloud mail.

I've decided that I will login both my outlook and icloud-mail accounts via IMAP on thunderbird and would then simply copy everything from outlook->icloud.

The problem I'm facing is that I can't login on thunderbird. When I enter my custom-domain email thunderbird finds the correct imap/smtp hostnames etc., but when I try to login using an app-password (2FA is enabled) I get an error stating username/password doesn't work.

I also tried it with my @icloud.com mail, following this article: https://support.apple.com/en-us/HT202304

But this ended with the same result. Now is it even possible to login with IMAP to my custom domain mail?

Answer 1

This turned out to be an error caused primarily by proxy-servers. I was trying to do this stuff on my company computer, which obviously also runs on company network so a proxy is being used.

Still though, you can't use IMAP with your custom domain email, you need to use your @icloud.com mail and have your username as everything before that domain, so use max as username if your mail is [email protected].