i have problems with sending mails to gmx. I always get a TLS handshake failure when sending mail.
I tested with other providers which work fine. Google, Vodafone work fine.
My setup is as following:
- Mailcow on a dedicated VM behind NGINX Proxy Manager
- All ports are forwarded to Mailcow
- Copied the Certs (cert1.pem -> cert.pem and privkey1.pem -> key.pem) from NGINX to Mailcow and disabled Letsencrypt on Mailcow, restarted Mailcow
- Certs are only for mail.mydomain.com, not autoconf .* or autodiscover.*
I tested my config with https://www.checktls.com/ but this is also showing me a TLS error:
Cert VALIDATION ERROR(S): unable to get local issuer certificate
Mailcow logs show me for example:
SSL_connect error to mta7.am0.yahoodns.net[126.96.36.199]:25: Connection timed out
I dont know how to debug further 🙁