A client of mine recently asked me this question. It’s a good one I hear all the time. This particular client designs and manages their own broadcast emails with a web based app built by local email marketing gurus, eROI.

First off, SPAM filtering is some of the worst voodoo out there, so all the info herein is totally based on my experience in email design.

Being mistook for a spammer is typically due to the composition of your broadcast email. Social spam marking functions aside, spam filters are usually based on a point threshold system. Incoming emails are scored bad points based on a list of predefined spam-ish characteristics. Once an email scores a certain level of bad points, the server marks it as spam. Depending on your email provider’s settings, the next course of action may be to deliver the message to a special “junk” mailbox, or delete the message altogether.

Here’s a couple of things that I think are probably the most common mistakes you can make when composing a broadcast email. In my experience, these are quick ways to get yourself bad points. This is by no means comprehensive, and each ISP may have it’s own spam criteria.

- Weird characters, sales text, and all caps in the subject line or From address. Real spammers try to get creative with call-to-action text and cr/\zy characters in the Subject or From fields. Not surprisingly, spam filters are clamping down on such abuse. So, try and step back from it and view the text strictly on a logical plane. Do the words or phrases shout “I’m Junk Mail!” ?

- Content that is mostly an image. I know it looks good, and it’s way easier than coding the HTML, but to a spam filter it looks like you’re hiding something. The filter can’t tell what the image says or looks like, so it gets nervous about letting it through. So, it may mark the email with a bad point, just in case.

These are just a couple of areas that I can confirm the filters take into consideration. Thankfully, there are services and features built in to many email list management apps that will test your email before you send it. Lately, I’ve been a fan of iContact, and they’ve built in a spam point checker. Not sure if the eROI guys have one, so check with them.

I have Hotmail, Yahoo, and Gmail email accounts strictly for spam testing, and I leave the filter settings at the default. Before a blast goes out, I send it to all of my addresses and make sure it doesnt get marked as spam.