How to make a mail server for several domains?

Question

Mail server

Hello. Is it possible to set up a mail server for several domains on one machine. I need to send letters from abc.ru, cde.ru, fgh.ru let's say. Do I need to purchase an SSL certificate for each domain for the mail server, or is it already too much and a self-signed certificate will suffice? The main thing is to configure the DKIM signature. Thanks in advance.

Answer 1

Agree with previous answer.
About letsencrypt. The certificate can be obtained for free, but you will have to renew it every 3 months. Therefore, IMHO, self-signed is enough for mail.

Answer 2

As already said, you can.
There may be one certificate for different domains via SAN SSL, or there may be several.
In the latter case, each domain must have its own IP, or use the SSL SNI mechanism, which is not supported by all clients. In particular, problems have been noticed on Android 4.
Self-signed certificates are an option, but ugly. I recommend the free Let's Encrypt (handy) or StartSSL (not too).

Answer 3

Can you suggest how to bind two certificates for different domains to one instance of the mail server? A bunch of dovecot + postfix, each domain has its own IP.