OK, I have the latest ISPC on Debian 7.11 Wheezy. I have my server running at www.myserverdomain.com. I have my mail running at mail.myserverdomain.com. I just went through all of the steps to Secure the Server with Let's Encrypt. Now, I can neither send, nor receive mail. I am not sure where to start. Can someone help me get my mail functional again? Can I make my mail server www.myserverdomain.com as well?
The guide you mentioned is for securing a single server setup but yours is a multi server setup with different subdomain for each server. Thus, I think you might need to modify the guide to suit your multi server setup. At the same time, do check your log for mail errors to identify your mail real problems. For instance, if postfix and dovecot complained about missing SSL certs, you might need create LE SSL certs for mail.myserverdomain.com or copy them from www.myserverdomain.com server to your mail.myserverdomain.com server. I haven't had any experience of establishing a multi server setup secured by LE so I am personally not so sure about it. Do some research and/or wait/get professional advices/helps.
It's only one server. There was a hostname mismatch, which is why I was wondering if I could make the mail server also www.[myserverdomain].com rather than mail.[myserverdomain].com
I understand wrongly then. There are some post on how to change hostname if that is what you want to achieve for now, so, do search for it to guide you in doing so.
I guess its ssl on mail service. The hostname mismatch could be due that. Did you see if you are able to send-receive emails with webmail, try to use hostname instead mail.yourdomin.com in incoming/outgoing server settings?
