Why do ISPs and other domains ‘silently delete’ my e-mail and how can I detect it?

Published on .

The term “silent delete” refers to the practice of some ISPs and other receiving domains to delete e-mail without providing any bounce or other notice to the sender. It’s predicated on the belief that by returning bounce data to spammers they’re better equipped to continue their abusive practices. Unfortunately, spammers aren’t the only ones impacted by the silent delete practice.

Silent delete is a controversial practice in both the sender and receiver communities. Many of the larger ISPs, such as AOL and Yahoo, have discontinued the practice, but Microsoft and others continue to use it unabated. The practice is particularly prevalent among smaller ISPs and, as b-to-b marketers know, at corporate domains. The quarantine function of many corporate spam filters that intercepts e-mail between the gateway and in-box and automatically deletes it, with or without recipient review, is a form of silent delete.

There are several strategies you can employ to detect a silent delete. First, organize your delivery data by the ISPs and domains that are most important to you. (This is a function that a good bounce management system should enable you to do.) Examine your delivery, open and click rates. If you see reasonable delivery rates but no or very low open and click rates, that’s a good indication that silent delete may be occurring. Second, on major ISPs, look at the mailbox monitoring data from your deliverability service provider (DSP), such as Pivotal Veracity, Return Path or Habeas, and compare it to the delivery stats from your bounce management system. If you see a number of “missing”’ seeds from your DSP but reasonable delivery from your bounce management system, that too may be an indication of silent delete.

In advocating a discontinuance of the silent delete practice, the place to start is at home. Check out what your own corporate spam filter is doing and suggest a change if you find that your company is engaging in the practice. Of course, you’ll also want to contact the ISPs and other domains that silently delete your mail and let them know what you think of the practice. And you should let your voice be heard at Messaging Anti-Abuse Working Group (MAAWG) and other industry groups that are examining this practice.

Dave Lewis is VP-market and product strategy for StrongMail Systems (, a provider of e-mail delivery servers and software.

Most Popular
In this article: