I have some issue with lets encrypt certificate on one of my subdomains - mail.programyzadarmo.net.pl. It worked but for some reason letencrypt auto renew has stopped working so yesterday I generated a new auto certificate using the DirectAdmin panel. I have no issues for programyzadaro.net.pl domain and blog subdomain but mail.programyzadarmo.net.pl shows wrong date - https ssl certicate will be served with a valid time of: Sat, 17 Aug 2044 .
My domain is: programyzadarmo.net.pl
The operating system my web server runs on is - Centos 7.9
I can login to a root shell on my machine - Yes
I'm using a control panel to manage my site - Direct Admin
Thank You 
Hello @olobambolo,
I know nothing about DirectAdmin so I won't be able to help here but yesterday you renewed the certificate for your domain mail.programyzadarmo.net.pl and it is the cert shown when reaching your site here https://mail.programyzadarmo.net.pl but you are serving a self-signed certificate when you try to reach your server using smtp and imap ports.
This is certificate served:
Issuer: C = GB, ST = Someprovince, L = Sometown, O = none, OU = none, CN = localhost, emailAddress = webaster@localhost
Validity
Not Before: May 13 00:13:50 2016 GMT
Not After : Sep 28 00:13:50 2043 GMT
So you should try to know why your DirectAdmin panel is using this certificate for smtp and imap instead of your renewed and valid certificate.
Good luck,
sahsanu
Problem solved, I re-added the subdomain in DirectAdmin
Thank You