Situation: 2 unrelated domains (with respective subdomains) on the same physical multi-protocol server, same IP, same registrant.
With Apache, no problem: thanks to virtual hosts, I can serve different certificates according to which domain was requested.
But the mail servers I installed (OpenSMTPD + Dovecot) don’t support virtual hosts (AFAICT). So they can’t serve a different certificate depending on the domain name by which they were contacted.
Now, I know I could just tell certbot to request one single certificate for both domains and all their subdomains; but I’m afraid the result will be a set of huge files (just guessing here, I have no experience).
Since I like to keep my websites snappy, I’d like to maintain separate certificates/keys for the 2 domains. Then, only for the mail servers my idea would be:
cat domain1-fullchain.pem domain2-fullchain.pem > sum-fullchain.pem cat domain1-privkey.pem domain2-privkey.pem > sum-privkey.pem
and let them use the summed fullchain and privkey for their TLS connections. The question is: will this work?
Thank you LetsEncrypt.org and community.