If you'll be using your own HTML to create your MailChimp campaigns rather than one of our available templates, there are a few things you'll want to keep in mind while creating your content. Below, we go over some common errors made when creating HTML emails and show you how to avoid them in your own code.

In this article:

Images, Links, and Graphics

Your HTML Email is Just One Giant Graphic

We don't recommended using just a single graphic as your email content. Most email programs block the automatic downloading of images by default, so your recipients will initially see a blank email and will either delete it immediately or even report you for spam. As a general guideline, we recommend having a ratio of 80 percent text to 20 percent images. However, all spam filters use different criteria for what is a healthy balance of graphics and text. Use our Inbox Inspector to test your content to see if it could be flagged as spam.

If you're just sending a simple invitation or promotional piece to your recipients and all it needs is a single graphic, you can still include text in the footer area. Your unsubscribe link, physical address, and list permission reminder all count toward the text-to-image ratio.

Hosting Images on a Local or Private Server

If you do work on a staging server or network drive, the general public won't have access to those servers, so images will be broken. To avoid this, upload and host all images on a public server so that they display correctly in your email. If you don't have a public server,  upload the images to our server and then link to them in your email.

Not Using Absolute Paths for Images and Hyperlinks

Absolute paths for images and files include your server information so the email application your subscriber is using knows where to locate and download the file. To be sure your images and links appear like they should, host all of your images on your server, then use absolute paths that point back to your server. So, instead of coding an image like this:

<img src="/images/photo.gif">

You would code it like this:

<img src="http://www.mysite.com/email/images/photo.gif">

Same goes for hyperlinks. Instead of a link like this:

<a href="index.html">Click here</a>

You'd code the link like this:

<a href="http://www.mysite.com/index.html">Click here</a>

If you're coding your emails locally with some kind of WYSIWYG application, they'll often keep graphics in a folder on your computer and reference them with relative links, rather than absolute links. Always make sure you go back and check that all <IMG> tags use absolute paths. One little tip is to go ahead and upload all your email's graphics to your server at the very beginning of your project. That way, you'll have to use absolute paths from the start. 


Not Testing Your Campaign Fully

Before you send your email campaign to your entire list, you'll definitely want to do some testing. To ensure the best possible result, we recommend sending tests to all the popular web-based email services, like Yahoo, Hotmail, and Gmail. Depending on your audience, you might consider setting up AOL and Comcast accounts if possible, or set up accounts with major ISPs in your area. You can also use the Inbox Inspector tool to preview how your email will appear in multiple clients or refer to our campaign testing tips.

Not Testing Emails Created By a Web Designer

If you asked someone else to create your email for you and you're simply pasting in the code he or she gave you, don't just trust that it will work as expected. You'll need to send yourself some test campaigns and make sure everything displays the way it should. Be sure to check that it wasn't designed too wide to fit in the preview pane of most major email programs. It's a good idea to test the images and links to make sure they work as expected and are set up as  absolute paths.

Coding and Software

Using Microsoft FrontPage, Word, or Publisher to Create HTML Content

When using Word, Publisher, or FrontPage to generate your HTML content, extra code can be added to your campaign inadvertently. This code can break your email design or even result in your campaign getting filtered as spam. You should only code HTML email in a good old-fashioned text editor and then import the template or paste the code into MailChimp.

Using JavaScript in HTML Email

Most email applications block JavaScript as a security measure. Make sure your code doesn't contain any JavaScript such as on form submit buttons, pop-up window links, image pre-loaders, widgets, etc. If you're copying HTML from an existing web page, make sure you clean the code of all JavaScript. While our Campaign Builder will remove any JavaScript we're able to detect, we still recommend  testing your campaign thoroughly before sending to ensure it displays correctly.

Using CSS Incorrectly

Most email applications strip HEAD and BODY tags from incoming email to keep embedded CSS from interfering with their page CSS. We recommend using inline CSS or embedding your CSS just above your content below the BODY tag.


Using Spammy Content

We all get spam. You know what it looks like. The subject lines are in all caps, letters are highlighted bright red or bright blue, they use lots of exclamation points, and they use phrases like "hottest," "best," or "click now!"

Keep your subject lines brief and to the point, keep your content relevant, don't try to use gimmicky catch phrases, and always  avoid spammy words.

Not Including Our Unsubscribe Link

We require all email campaigns sent through MailChimp to have  our  *|UNSUB|* tag. There's absolutely no exception to this rule. It must be present in both the HTML email and the plain-text email.

Not Including a Permission Reminder

All our built-in templates automatically ask you to create a permission reminder but if you're coding your own, you should always include one in your template code. Permission reminders briefly tell your subscriber how they got on your list, for example, "You received this email because you subscribed at www.example.com for our newsletter." Including a permission reminder prevents false abuse complaints, which could get your company's domain name blacklisted.

Not Including Your Postal Address

We now require that all our users include a valid physical mailing address on all emails sent through our servers in compliance with the  U.S. CAN-SPAM law. The address is automatically inserted whenever you use our built-in HTML email templates, so if you're coding your own you will need to add it manually.


Other useful resources

  • Free Email Marketing Guide
  • Inbox Inspector: Generate screenshots of your email designs in major email programs and test major spam filters and email firewalls, and scan for spammy keywords in one click. 

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