NOTE: This KB article provides guidelines for most installations regarding the items that need configured on your DNS server. It does not explain how to configure your DNS server.
There are three major items to set up on the DNS server for each domain added to SmarterMail: An A or CNAME record, MX record, and PTR or reverse DNS record. In addition, you may also be required to set up the SPF (Sender Policy Framework) record.
How you set up these records is dependent on who hosts your DNS server and the DNS software used. Check your DNS server documentation for instructions on how to set up the following records.
There are additional, optional records you can create as well. While "optional", to ensure proper mail server performance for users, these records are highly recommended. They include an autodiscover record, and DKIM.
WebMail URL (A Record)
Add an A or CNAME record for mail.example.com that points to the IP address of the Webmail interface. This will allow users of that domain to access webmail by typing http://mail.example.com in their Web browser.
Mail Pointer (MX Record)
Add an MX record for the domain that points to mail.example.com. This will allow other email servers to locate your mail server.
PTR (Reverse DNS Record)
PTR records resolve IP addresses into hostnames. By setting up a PTR record, the receiving server can do a reverse DNS lookup to verify the sender.
Some large email providers like Gmail and Outlook.com require specially formatted TXT records to be added to your DNS server. This special format is known as SPF (Sender Policy Framework). Information about how these records should be formatted can be found at a number of different sites on the web. Just search for "how to configure SPF" and you should plenty of resources to assist you. Please keep in mind that the owners of the domains may have significant input on what goes into these records.