Good evening fellow slackers,
I am trying to setup a little home server for myself and few friends, and one of it's function will be a mail server. I have some experience with small linux mail servers running Postfix, plus I have found some documentation on Sendmail, I think I should be ok there. But I am a bit confused with the hostname and mx record stuff.

Lets say, my /etc/hosts file looks like this:
*where xx.xx.xxx.xxx is my real IP address.

Now confision starts with mx record which is mail.mydomain.com and "mail" is not the hostname of my Slack box. So the question is: should I change my mx record to myhostname.mydomain.com, or should I add mail to my /etc/hosts somethere? or maybe I should specify mail.mydomain.com somewhere in sendmail configuration and that's it? What do you think?

Now another question is related to Reverse DNS, I know, that for my server to be accepted as trusted by other major mail servers, I should ask my ISP to setup Reverse DNS for me, so when my server says helo i am xx.xx.xxx.xxx myhostname.mydomain.com to gmail, gmail then tries to resolve xx.xx.xxx.xxx into myhostname.mydomai.com and if it finds myISPdomain.com instead, then my mail is marked as spam (unvanted behavior). So again, maybe someone knows what my ISP shoud set for my Reverse DNS, is it myhostname.mydomain.com? Or just mydomain.com? Or maybe mail.mydomain.com?

If it's not too much trouble, I would like to hear your thoughts about tis matter.

When you say "real address" I'm assuming you mean LAN address (RFC1918), in this case the MX record should have an/the IP address on the outside of your firewall. It doesn't matter what name you use but your mail server should tell inbound connections the same name.

Some ISP's are not really interested in creating PTR records, in this case it's usually easier to forward all outbound email through your ISP's mail server instead which will provide validity as far as receiving MTA's go.

1 members found this post helpful.

Thank you for reply,
If I understood you correctly, and my smtp banner says hello I am myhostname.mydomain.com, then my MX and PRT records also should have myhostname.mydomain.com?

In my case, I can get PTR record easy, since a lot of my friends work for my ISP, so everything is arranged already, I just need to tell them, where my PTR should point.

Correct