Email List Hygiene — Part 3: Keeping Your Code and Images Clean

In part two of this series on email hygiene, we touched on some characteristics that catch the attention of spam filters. Those five points suggested keeping your text well formatted and error free as strategies to make sure your message reached the intended inbox.

But text isn’t the only indicator spam filters use to flag messages. From here, we’ll move on to other aspects of an email that might get your messages unduly sent to the junk folder.

Avoid Image Heavy Emails

Because spam filters cannot read text in an image, they’re fertile ground for spammers to deliver their message. Messages with little to no text but use a large image or several images can trigger the spam filter.

Be Careful with Links

The same rules apply to links as images. Spam messages often consist of a link or several links and very little to no text. Since it is usually crucial to have links when marketing via email, just make sure to have quite a bit of text to go with them.

Another issue to be wary of is using URLs as links. Many spammers will use a well known URL but the actual link will go somewhere else. So, for example, the link may display “” but it will actually link to “”. Because of this, it is better to use descriptive text that links to a destination URL.

Newsletter File Sizes

The size of your message can also land your email in the junk folder. Since quite a lot of spam comes in at less than 20KB, spam filters typically look for emails that are very light. Try to keep your emails between 20KB and 50KB.

Use Clean Code

Programs like Microsoft Word have an HTML output option. However, the HTML code produced by it is horrible by internet standards and should never be used. Even copy and pasting from Word can create messy code which will be flagged by spam filters. Use email template creators like Aislelabs built-in template editor to ensure your code is clean.

Use Human Reply Addresses

All of your emails should come from an actual used email address. You should avoid addresses like or as it signals to your users you do not care about an open dialogue with them.

It is also important to use a personal name or brand name in the from field. Studies have shown that email recipients are likely to send a message to spam based on nothing more than what is in the from field.

Part four of this series will go over some best practices for interacting with your mailing list.

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