Deliverability News: Major Spam Filter Acquisition

Amanda DeLuke

Proofpoint has entered into an agreement to purchase Cloudmark by the end of this year.

As an email marketer, you’re probably familiar with their filtering mechanism. You even may have experienced issues getting mail delivered to recipients who use those filters.

Prior to the announcement of the acquisition, Proofpoint changed the way they remediate blocks which now provides a mechanism to submit support tickets.

However, their rules to classify mail have also changed. This makes remediation more challenging, so as the acquisition progresses, deliverability will continue to be monitored.

Now that the agreement has been made, Proofpoint will be able to incorporate Cloudmark’s Global Threat Network into their current platform to provide extensive security intelligence covering email, social media, mobile and SaaS products.

You will likely notice a consolidation of how mail is filtered and how rejected mail is handled between the two platforms going forward.

As more advanced threats rapidly evolve, mail filters will adjust their rules. This will lead to an additional scrutiny on inbound mail (especially due to an uptick in spear phishing attacks).

Senders should focus on these 3 major deliverability components to help properly classify mail: authentication, permission, and engagement.


There are 3 major components that senders should have configured on their domain(s) used in sending mail; SPF, DKIM, and DMARC.

  • SPF tells receivers where your domain’s mail should originate.
  • DKIM provides a mechanism for receivers to verify responsibility for messages received.
  • DMARC leverages SPF and DKIM for policy enforcement, telling receivers how they should handle mail that fails authentication.

Think of it like a license and passport to send email and what the protocol should be if those identification methods fail.


Only send to recipients who have opted in to receive messages from you. This is good practice to follow especially because it is illegal in many parts of the word to send without prior permission, which could lead to some hefty fines.

Sending to recipients without permission can also prevent mail from being delivered to those that want/need to receive it. It’s not worth the risk. Furthermore, having permission greatly reduces your risk for sending to spam trap addresses which could cause you to be blacklisted.


Finally, engagement. Gmail, Microsoft, and now many other mail systems rely heavily on user engagement. Sending to unengaged subscribers can cause some major deliverability issues.

This emphasizes the importance of keeping an updated recipient list and encouraging interaction from your audience. If your messaging ranges in content, frequency, and recipient groups, it may be necessary to separate these types of mail to maximize deliverability.

As marketing trends continue to move away from “one-size-fits-all” bulk mailing and move toward customized targeting through marketing automation, deliverability will naturally improve.

Additionally, following best sender practices is crucial to getting mail delivered because spam filters are constantly adapting their rules due to ongoing threats.

About the Author
Amanda DeLuke

As a Deliverability Specialist, Amanda helps with client sender reputation, abuse management, and internal deliverability process. When she is not busy at work, she enjoys playing the alto sax, mountain biking, and chasing after her identical twin boys.