Email Deliverability Series, Part Two.

Who done it? A delivery discovery...
How spam filters may block your messages, and what you can do about it.

Last issue we discussed some of the basics regarding spam filtering and how several PoliteMail features help you overcome some of the obstacles to getting your messages through.

In this issue we'll talk about a recent challenge a customer had with getting through the Yahoo mail filter, and the tools we used to solve it.

In this case, the customer first noticed the delivery problem when sending replies to job applicants who had submitted resumes via email. Having organized the resume emails into folders and importing each into a PoliteMail mailing list, she noticed she was not getting open responses from a couple of key applicants. Upon further inspection she noticed the in-common element was a Yahoo email address. Upon re-sending the same template message to her own Yahoo and Hotmail accounts, she found it went into the Yahoo junk folder, but it made it to the Hotmail inbox. Why?

TIP: Use the PoliteMail Preview Send command, before you send to your entire list. Preview will send a copy of your email message to a test list, so you can see how it looks when delivered and if it makes it into the inbox.

Using email metrics to examine the cause

To figure out what was happening, first we looked at the email metrics reports for several of her latest sends, and used the report by domain option to determine if there was a pattern of zero opens for Yahoo addresses. Two of the three messages had this pattern, so as some were in fact getting through, it appeared to be an issue with the content in those two messages. Each of the messages where quite different, so we sent them each to PoliteMail's new SpamScore™ service to help figure out what was happening.

The next step was to send a regular text "hello world" tracked email to both a Yahoo address and the SpamScore address. In this case, the message ended up in the junk folder, and also received the extraneous content SpamScore report. So we had the culprit, we just didn't know why yet. However, the message included both the "hello world" text and her signature. When she sent without the signature, it made it to the Yahoo inbox and received a 0 SpamScore. So now we had the problem isolated to the signature.

Mystery solved: The space character did it.

The signature she was using included a logo image file, created using PoliteMail's create graphic signature tool. When that logo was removed, everything went through to the inbox. So what was so unusual about the graphic file? It was named "New Logo" which seems fine, but the space character in the file name caused a increase in the spam filter points, which caused Yahoo to filter it out.

Technical Explanation: The url escape code for the space character is %20, which is used in the html code to reference the image file. Some spam filters apparently confuse the %20 as a content type delimiter, and report it as extraneous.

Conclusion: Don't use spaces in your image file names (or SmartAttachment™ names) when they are used for email.

Wondering why your legitimate commercial email isn't making it to the inbox? Now you can send it to SpamScore@politemail.com and find out.

The SpamScore™ service will run your email through a spam filter, and send you back the resulting score, along with reasons for any spam points it accumulated, allowing you to adjust your content. The SpamScore service is built into PoliteMail 2.0 and is also available as a free service.

The About.com email marketing guide rated PoliteMail 2.0 4½ stars out of 5.

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