Email security providers customers are typically organizations that are concerned about threats from malware, phishing, malicious emails, impersonation and spam.  As part of their solution, email security providers assess sender reputation and have block lists much in the same way as Microsoft and Google.  From an email deliverability perspective, they are an important indicator of sender reputation.  Even if they represent a small proportion ofyour lists, a poor reputation with one of them might be an indicator to problems elsewhere.

In terms of who the market leaders are, Datazag’s database of 265M domains lets us track which vendors are providing a mailbox provider service.  Here is a table showing the top 10.

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Proofpoint is by far the largest in terms of domains, but the others are also important players in this market and can influence your overall reputation. You never know who is sharing their findings with others in the industry!

So how do you check if you are blocked by one of these email security providers?  Firstly, most of these vendors allow you to check your IPs on their website.  Another way is to search your smtp logs for messages from these providers. These will tell you a lot about your reputation, highlighting domains and IPs that are in their spotlight.  In addition, you can plug in our data service to segment domains for email security providers which makes it easier to pay special attention to these platforms.

Another indicator is to identify email addresses that are generating a high number of clicks. This might be caused by one of these vendors checking every link in your email content to verify that it is not malicious.  Apart from skewing your engagement stats, this is not necessarily malicious.  However, it does indicate that you are under suspicion, and you are being evaluated or being watched.

In summary, email security providers are important players in terms of your email deliverability performance. They provide another window on your sender reputation which can provide valuable insight.

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