The pesky spam folder

A large part of my day is spent helping track down causes of emails going into the spam folder. I thought I’d share my testing process in case it helps you at any point.

I’ll start off by saying that most common variables in getting into the Spam folder are, in order of importance:

  • IP Reputation
  • Content of the email
  • From domain reputation

Just like any other investigation, you need to isolate one issue at a time to rule it out. The first one you can rule out is IP reputation if you are sending with Postmark. We monitor those guys very closely, every day. So if there was an IP issue, then we’d know about it. This leaves you with two variables: content and domain.

Content #

The first thing to test is the most common cause of problems I see. Content can seem completely legitimate, but then Yahoo doesn’t agree and marks it as spam. I don’t have any rules here, but here’s what I’ve found useful. Start with simple and then expand. Plain text to HTML. “This is test” to the full email. Remove links and add them back. Remember what we said about some URLs being flagged as spam? Make sure you are sending from the same IPs (Postmark) and the same From email. This way, the only thing you are testing is content.

If you are testing a particular ISP (I’m looking at you, Gmail), you may want to use multiple accounts. Sometimes adaptive filtering plays a roll, so if it’s only going to Spam in one account that could be it. We also have plenty of test mailboxes if you want us to look as well.

Domain Reputation #

In my experience, I’ve found that domain blacklists aren’t the only way to gauge if you have a domain-wide sending issue, but of course it should be considered. I like to use MX Toolbox and Return Path to check some of the top domain blacklists for any listed issues. Honestly though, if your domain is there, you must have done something pretty serious. So chances are, you’ll come up clean.

Once you’ve isolated that it’s not a content issue, and your domain is not listed anywhere, I usually recommend testing with multiple from domains. To do this, you would send the exact same content, through the exact same IPs (in this case through Postmark) but with different domains. Don’t send sample content though. Send the content you intend to send. Remember to keep all other variables exactly the same.

At this point, hopefully, you find the cause of the problem. If you still aren’t able to isolate the issue, email me. I’ll see what I can dig up. And if you have got an IP reputation issue, why aren’t you using Postmark?