I have also tried multiple other mail clients and so far none of them had connection problem to my mail-server other than Mailspring. Can someone help me fix this issue.
I’ve also used Thunderbird and Geary both shows the valid let’s encrypt certificate and connects without problem. I only face this certificate issue with Mailspring.
Edit: I also use the mail-server on the Gmail Android app without any issue
Unfortunately, it is hard to check this without being able to check the certificate. If you want, you can send me the Server URL by DM and I can have a look. No promises that I will be able to solve this, though.
Might be stupid of me, but I don’t see an option to DM you here. I am willing to share the Server URL but I may not have enough permissions to DM you. Shall I also create a dummy mail for you to test?
I’ve fixed the issue. Mailspring was using my Helo hostname for some reason. which was set to my root domain. I’ve reconfigured it to my FQDN and reissued SSL. Now it works.