you need to create the "A" record & MX record with whoever is hosting your authoritative DNS. In this case it sounds like NetSol is doing that. Point being, this is how the rest of the world finds you - a DNS lookup. Which DNS is the question. You can host this if you want, but it is better outsourced to someone with multiple datacenters etc.
Whoever is hosting your DNS will be setting up a zone file for you. You need something like:
Zone: mydomain.com
@ IN A <ip of server>
- this IP can be the mydomain.com server or pretty much whatever you want it to be.
Now you need mx (mail exchange) records. You can have up to 5 of these. It's the only part of DNS which is built for redundancy. lower # = higher preference. This is how other mail servers find your mail server to send you stuff. Their mail server is told (by a user) 'send an email to bob@mydomain.com Their mailserver then makes a dns query to find the MX record for mydomain.com and attempts to contact it. You add lines like this to your zone file:
@ IN MX 5 mymailserver.mydomain.com.
@ IN MX 10 mybackupmailserver.mydomain.com.
That will get mail coming in. Be sure to have them set up a reverse PTR record - many servers will no accept mail from servers who do not have these records set up. Aka the in-addr-arpa.
Also make sure your server identifies itself with the correct name when queried. If your server's dns resolves to "mail.mydomain.com" make sure that it how the server ID's itself when it responds to other servers. To test this, telnet to port 25 on your mailserver and see how it ID's itself. Go out to dos, type telnet 11.22.33.44 25 (enter)
the server will respond with something like:
"220 mail.mydomain.com etc etc etc.. ready
Last, to help you troubleshoot, use
to get an idea of how you look to the world.
have fun!
