Why Do Emails Get Marked As Spam?

Spam filters have a long list of criteria when judging the “spamminess” of an email.

They’ll weigh each factor and add them up to assign a spam score, which helps determine whether a campaign will pass through the filter. If the score exceeds a certain threshold, your email will get flagged as spam and go straight to the junk folder.

Each spam filter works a bit differently though, and “passing” scores are typically determined by individual server administrators. (This means that an email could pass through Spam Filter A without issue, but get flagged by Spam Filter B.)

Let’s learn about 5 factors that contribute to being marked as “spam” and sorted into Google’s “bundles”.

1. Campaign metadata

Metadata literally means “data about data”.

For emails, metadata is the information about the sender, the recipient, the IP address the email was sent from, the recipient’s IP address, the email’s timestamp, etc.

Spam filters look at the metadata of your emails to make decisions.

Here are a few things to keep in mind about your metadata to help avoid the spam filter:

  • Use merge tags to personalize the To: field of your campaign
  • Ask recipients to add you to their address books
  • Ask recipients to reply to you (more on this later)

2. Images and email templates

Email templates look great… But could they be hurting your conversions? 🤔

The “Google clip”

Email clients like Gmail “clip off” messages larger than or equal to 102 kB at the end:

The “Google clip” on mobile

📧 How does email clipping hurt you?

One of the biggest problems with email clipping is that your subscribers who use Gmail won’t see your whole email!! (Unless they click “View entire message”, which they won’t.)

You also might not be able to accurately track your open rates when your emails get clipped. That’s because the tracking code is usually at the bottom of your email.

If multiple images and email template aren’t enough to get you sorted into spam, it will certainly trigger Google to sort your message into the “Promos” tab.

Here’s a few things to keep in mind about the SIZE of your emails when you’re trying to avoid spam filters:

  • DO NOT COPY AND PASTE DIRECTLY FROM A WORD-PROCESSING PROGRAM. Doing this sometimes adds extra formatting code to your email without you realizing it. Always be sure that you are selecting “Paste without formatting” or Cntrl + SHIFT + V (Shift + Option + Command + V on Macs) if you’re pasting text into your email marketing software.
  • Don’t use too many images, consider compressing your images or not displaying images in full size in-body.
  • Be careful when including logos! Have you compressed the image file of your logo?
  • Minimize your code with tools like HTML Minifier and HTML compressor. (Especially helpful if you really, really want to use email templates. But you really shouldn’t. Stick with text-based emails.) Note: Make this your last step because code is hard to read and work with once it’s minimized. <<< This is a great tip for advanced email marketers with large databases in the hundreds of thousands or millions
  • Send a test email to your personal email address to make sure it’s rendering correctly.

3. Avoid URL shorteners

Using sites like Tiny.url or Bitly to shorten your links often triggers spam filters.

4. Bounced emails

Part of the basic CAN-SPAM regulations includes promptly removing bounced email addresses from your database.

Because of bounced addresses impact your deliverability negatively in the eyes of email providers and ISPs.

That’s why list hygiene is so important! 🛀

5. Avoid Spam Filter triggering copy

Email services like Gmail have a few rules about the actual text of your emails that triggers the spam filters.

It’s hard to create a comprehensive list because of just how many different email providers there are, but as a start you’ll want to avoid…

  • ALL UPPERCASE LETTERS (especially in the subject — a study by the Radicati Group shows more than 85% of respondents prefer an all-lowercase subject line to one in all caps.)
  • Unusual punctuation (such as multiple exclamation points!!!!), especially in the subject line
  • Specific pammy words and phrases (such as free, buy, purchase, earn big bucks, and money making — this is a GREAT list with a bunch of spam trigger words)

Can I Improve Email Deliverability Of A Bad List?

If you get too many spam reports, email providers start automatically filtering ALL messages sent by you.

Is there a way to overcome this?

A 2015 Email Evolution Conference (EEC) panel discussion with representation from Gmail (Sri Somanchi), AOL (Paul Rock), Comcast (Matthew Moleski), and Outlook.com (John Scarrow) revealed 7 User Actions That Impact A Sender’s Deliverability:

#1 — Opening an email = Good 😊

#2 — Deleting an email without opening it = Bad ☹️

This indicates recipients took a quick look at the subject line and sender address and determined that they weren’t interested in the email.

#3 — Moving an email to a folder = Good 😊

If recipients are taking the time to move messages around, they’re indicating a level of interest.

#4 — Junking an email = VERY BAD 😦

This is a strong indication that the recipient doesn’t want to receive the emails. (AOL automatically puts messages from that sender in the junk folder when recipients mark a sender’s email as spam twice.)

#5 — Moving an email from the junk folder to the inbox = Very good 😄

This indicates that a recipient has an interest in receiving these emails. (For AOL, it takes just one time of moving an email to the inbox to reset the previous spam classification.)

#6 — Adding a sender to the address book = Good 😊

This indicates that the recipient is engaged with the sender.

#7 — Replying to an email = Very good! 😄

A reply is a strong indication that a recipient is engaged with the sender.

Why are MY emails getting marked as Spam?

Google has a helpful troubleshooting tool if you want more specific guidance on how to change your messages.

Now that you understand the basics of why emails get marked as Spam or sorted into “batches”, let’s look at some real world 🌎 case studies so you can SEE what emails make it into the priority inbox 📧



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