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Have you ever tried to send a marketing email to your members, only to have your message get blocked by a firewall? 

Email marketing specialist Amy Hage, co-founder of Strategy Maven Agency, shared helpful insights and tips on understanding spam filters and improving email deliverability. Read on for her expert take on email marketing that reaches your members. 

Email Firewalls and Spam Filter Triggers

The purpose of email firewalls is to remove spam and malicious content from incoming emails. What constitutes as spam is determined by rules set by the email server. When a firewall identifies an email as spam, the message won’t reach the intended destination — the recipient’s inbox. 

What causes an email to be flagged as spam?

Spam filters are triggered for a number of reasons, from the words you use to your sender reputation. In terms of content, Hage said anything that sounds false or misleading, exaggerated, gimmicky, or pressuring may be flagged by a spam filter. 

A small sample of common words to avoid include: 

  • Act now
  • Click here
  • Buy 
  • Call now 
  • Free
  • As seen on
  • What are you waiting for?
  • Guarantee
  • Limited 

Other potential spam issues include typing in ALL CAPS, using excessive punctuation, linking to unsavory websites, sending an email with broken HTML, or using too many images. 

Email Flagged by a Spam Filter or Firewall? Here’s What to Do:

If you tried to email your members but were unable to get through to your members’ inboxes, Hage recommends first taking a step back and asking the following questions: 

  • How did I obtain this user? Did they willingly and knowingly sign up to receive my emails?
  • When the user subscribed, did I ask them to save my address?
  • Am I sending this from a generic address like or 
  • Am I providing them with a way to unsubscribe?
  • Am I actually spamming? Is this content that the user wants to see?

After assessing and determining that your email list was built organically, users have an easy way to unsubscribe, your content is valuable, and you are not sending emails from a generic address, Hage offered the following tips for improving your email deliverability: 

  • First, ensure that you are not violating any spam laws, like those set forth in the CAN-SPAM Act. Compliance requirements include, but are not limited to:
    • Using clear and honest subject lines and disclosing when a message is an advertisement
    • Including a physical postal address
    • Using factual and accurate header information
    • Providing a clear path to opt out and honoring those requests quickly 
  • Test your HTML to ensure it’s not broken, and make sure you use and enable plain text.
  • Keep your email send cadence consistent. Suddenly sending more emails than normal may be a red flag. 
  • Make sure you are using a reputable Email Service Provider — these often come with features that help ensure better deliverability. 
  • Look into getting a dedicated IP address for sending emails. 

How to Get the Best Results from Your Email Marketing

If your members have government or university email accounts and computers with sensitive firewalls, Hage recommended asking them for their personal email address. This may help improve deliverability and overcome common engagement challenges. Another tactic is to ask your recipients to save your email address as a contact. Don’t be afraid to simply survey your list, either, to learn what kind of content they want to see from you. 

“Ensure you’re always testing to see what works for you and your contacts,” Hage added.

Overall, for associations to garner the best results from their email marketing, Hage’s parting advice is: 

  1. Do not purchase lists. 
  2. Ensure you have permission to send. 
  3. Use a double opt-in 
  4. Clean your contact list regularly. 

And don’t forget: Always make your emails easy to unsubscribe from!

Looking for more resources on email marketing? Read: How to Grow Your Newsletter Under Apple Email Privacy Change

Emily Herrington
Post by Emily Herrington
August 30, 2021
Emily Herrington is a New Orleans-based digital marketer specializing in SEO, content, and pay-per-click advertising. She can usually be found at her desk obsessing over data and rankings, or in the kitchen covered in flour.