I've got a mailserver and the hostname is mx.domain.com. Of course the server is configured to send emails to $mydomain and/or $myhostname.$mydomain in Postfix. Do I need to create the CSR/key for the FQDN or just the domain?

I am using Dovecot for the MDA. The mail client I decided to go with is a very bare bones simple one called Trojita on Linux, but even Thunderbird is okay. The issue is that I am not able to use submission on 587 with a self-signed certificate. Am I forced to buy one or could I use LetsEncrypt for this?

1 Answer 1


The name in the certificate has to match the name the client uses to connect. If you enter mail.example.com in the e-mail software, the certificate has to be for mail.example.com.

There's no reason you can't use letsencrypt for this.

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