How to Host Email Servers

Host your mail server on a static IP address. If your IP address changes too frequently, other mail servers might not be able to connect to your server. A static IP address never changes. If you are leasing a dedicated server or co-locating your server inside your hosting provider's facility, then you have already been assigned a static IP address. If you're running a mail server from a home or small business Internet connection, then you might have been provisioned a dynamic IP address. Ask your Internet service provider to upgrade you to a static IP address if you don't already have one.
Establish reverse DNS records. Unsolicited email is such a problem that many email servers routinely reject incoming email unless it appears unlikely to have been forged. A reverse DNS record, also known as a PTR record, links your server's IP address with your server's domain name. Creating this link strengthens the credibility of your server and makes other mail servers less likely to delete your mail. To set up a reverse DNS record, you must ask your domain name administrator to create the record on your behalf.
Create DNS 'MX' records. The Domain Name System (DNS) is the service that a computer uses to look up a server's address. DNS supports a special record just for mail servers: the 'MX' record. These records, also known as 'mail exchanger' records, map domain names into mail servers. If your mail server is called 'mail.mysite.net', for example, then you need an MX record pointing from the domain mysite.net to the server mail.mysite.net. Ask your DNS administrator to set up your MX records on your behalf.
Disable mail relaying in your mail server's configuration. In modern email deployments, a mail server is supposed to accept mail addressed to only one domain name. Nevertheless, a mail server may still choose to accept any mail as long as it forwards the message to its destination. A mail server that accepts any mail is an open relay. Because open relays are responsible for so much unsolicited mail, most mail servers block mail from an open relay whether it is legitimate or not. To avoid this situation, check your server's configuration and make sure that it accepts mail only for its own domain name.
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