My domain details are smtp.domainname.com and pop.domainname.com by using these values I can send emails but I cannot receive any emails from other emailing systems. The problem lies at POP obviously. I created a CNAME RECORD as POP.domainname.com but results no use... Do I need to create any other record like A RECORD or MX RECORD or other as POP.domainname.com to receive my mail?
Email servers send and recieve email via SMTP, not POP. Email clients download their email via POP. My suggestion would be to check your public DNS namespace to make sure you have an MX record for your domain and to also check your firewall to make sure you're allowing inbound SMTP traffic to your email server.
Are you sure the problem is DNS-related? To verify this problem, you must verify the DNS record is right. I mean, it's pointing to your pop server's Ip.
If it isn't dns-related, you should: - check logs in the server related to pop. You should look for activity and/or errors. - you can test pop service from inside the server. Access the server and make a telnet to port 110 and wait for prompt.
Without knowing more details about your domain and setup it is hard to say, but start by creating MX records pointing to the host (A) record that points to the IP of the server that you are using to receive mail.
You should also set up reverse DNS (a PTR record) for your SMTP server, as this makes it less likely to be flagged as a source of spam.