It's fairly common to encounter a problem when setting up a private email server; your outgoing email sometimes gets classified as spam. WHOOPS! This is usually due to a couple possible issues:
- Your email shares too many similarities to actual spam.
- Your email server and DNS records aren't configured properly.
Composing a good email is something of a skill, and there are a few rules you can follow to not be flagged by spam filters. First, you should definitely pay attention to what kind of content your sending and how you're formatting it. If you're editing it with HTML, make sure your code is clean and compatible- or that you're using an email builder that can do so. In terms of content, most of the email should be written. A general tip is to make sure the text in your email takes up more space that images or links. Finally, avoid obvious, attention-seeking language like "buy now" or "get rich quick," and avoid ALL CAPS if you can. The closer your email looks like an actual letter someone would write, the better.
Actually configuring a mail server, on the other hand, is quite a bit tougher. The most common solution for running a mail server is a network of running a mail transfer agent (MTA) - usually Exim or Postfix; IMAP/POP3 server Dovecot, and SpamAssassin (a spam filter). There are feature-complete deployment solutions out there too, iRedMail for instance. It would take a while to go through each of those, but if you follow the links you'll find extensive resources to help you through the setup and they're all open-source!
Once you have your mail server up and running, it's a good idea to send a test email to MailTester.com to be verified. This service evaluates the structure and content of your email and let's you know the likelyhood of it getting bounced, as well as reports errors it finds in the mailserver configuration.
When configuring the DNS on your mail server, it's important to pay attention to implementing DomainKeys Identified Mail (DKIM) authentication and DNS records like PTR, DMARC, and SPF.
DKIM lets you electronically sign emails to validate your email server's domain, and it uses a text (TXT) record to do so. SPF is used, basically, in the same way; with a TXT record that provides a range of servers that can send email from the same domain.
PTR records are used for reverse DNS lookup, using your IP address to get the associated domain. Nearly all mail without a PTR record ends up in spam folders, so this one is a good one to keep in mind.
Last thing we'll cover today is Domain Message Authentication Reporting and Conformance (DMARC), which is a system designed specifically to combat spam. It checks DKIM signatures and SPF records, and if your mail passes either one of those checks, that mail is considered DMARC compliant.
If you're just starting out, everything we've covered today is very important to consider if you don't want your email server flagged as a source of spam. We strongly encourage you to follow those links and learn more about running a web server. Hope it helped you out.
Our ServerSuit platform is fully capable of helping your setup and run an email server, so give it a shot. You get a 30-day FREE trial when you register, or rent a server, with us so trying it is risk free.
Until next time!
This article was originally published in July 2017