Hi @ranch
please read your older topic - Problem with expired cert
Same situation - you have created the certificate - https://check-your-website.server-daten.de/?q=inwtx.net#ct-logs
| Issuer | not before | not after | Domain names | LE-Duplicate | next LE |
|---|---|---|---|---|---|
| Let's Encrypt Authority X3 | 2019-11-11 | 2020-02-09 | mail.inwtx.net - 1 entries | duplicate nr. 1 | |
| Let's Encrypt Authority X3 | 2019-11-11 | 2020-02-09 | inwtx.net, mail.inwtx.net, www.inwtx.net - 3 entries | duplicate nr. 1 |
If you don't use a webserver with mail..., why do you want to install the certificate? So change your command -> certonly is enough. Or create a matching vHost. But checking your mail subdomain, there is the wrong certificate with two domain names and there is no mail port.