I have tried for a long time, but have not been able to solve this problem:
My cyberpanel has a domain name, domain.tld, and I use mail.domain.tld as its mail processing domain. After setting up the DNS record, my webmail can send and receive emails normally, however, I can’t login successfully on external email clients (such as Gmail, Hotmail, QQ mail, etc). They keep telling me “Outbox login/authentication failed, please check username and password”. I am sure my password is correct, so I suspect that it is a “short user login” problem. However, the problem is the same whether I use [email protected] or username. I searched some tutorials and tried to set it up on snappymail’s admin panel, but even after setting it up on snappymail’s admin panel and testing it successfully, I still can’t log in on the external email client.
mail.domain.tld and domain.tld are all encrypted. Ports are 993 and 465.
Some posts seem to have encountered the same problem as mine, but no suitable solution seems to have been proposed.
If anyone can help me I will be grateful. Thanks.