The number one reason why email newsletters don’t get delivered is because they are blocked by spam filters.
How do spam filters work?
“Spam filters are like bingo cards. The have a checklist and if an email ticks enough boxes on the scorecard … bang … the door is slammed in its face.”
The only way to find this out is to check your open rates. You can only do this if you are using an mass email system that can monitor and report on open rates. If there is an unexplained dip in your open rate, the chances are that the email has been blocked.
Guidelines to avoid being blocked
1. Know the words and phrases that spam filters search for.
Some of these are obvious but not all. It is worth looking at spam trigger word lists to get an idea.
2. Think carefully about your subject line
Spam filters focus particularly on the subject line. As well as avoiding the words mentioned above, don’t use capital letters or too many exclamation marks.
3. Text/HTML and all-image emails
HTML emails are more likely to be blocked. It is a good idea to do a text version if you send an HTML newsletter.
If your email is a single image it is even more likely to be blocked. Also some firewalls strip out images so the email will just look like a blank page.
4. Try to avoid sloppy HTML
This often happens when an email has converted from Word into HTML. It is always best to prepare your copy in a text editor such as notepad to avoid these problems.
5. Minimise your use of colour
If you use text colour and different background colours, the spam filter will be alerted and will look for other criteria that may lead to being blocked.
6. Limit your use of attachments
We all need to send them sometimes but spam filters and firewalls will often block emails with attachments as they have a high risk of containing viruses and other nasty greeblies.
7. Watch the size of your file
Most spam is under 20KB so emails with more text will be more likely to get through. The ideal file size is 20k – 50k.
8. Be careful using the BCC field
If you use the BCC (Blind Copy) field for your email it could get marked as spam
9. Check your copy before you send it.
If you are not using a system that can check your copy for spam, here are two free tools that you can use:
Programmer’s Heaven Spam Checker http://www.programmersheaven.com/webtools/Spam-Checker/spamchecker.aspx