Best Practices, Delivery Essentials, Industry Updates

Don't be so quick to suppress those mailbox full bounces

Over the years, it has been a common practice to convert certain temporary bounces into permanent bounces after a series of occurrences. Some ESPs will escalate bounces that occur X number of times in a row, or occur for X number of days without a successful delivery. One of the most commonly affected bounce types for these suppressions is Mailbox Full.

Mailbox full/over quota bounces are considered by many to be a symbol of a dead address. With the nigh-unlimited storage found in most mailboxes these days, no one who actually checks their email should ever have a full mailbox…right?

Not necessarily. In a new blog post on the MessageGears blog, I sat down with Senior Product Owner of Cloud Operations Nick Zeich-Lopez (aka. ‘Mr. Data’). We pored over results from over 20 billion deliveries and found some surprising results.

For starters, the data showed that of those recipients who experienced a Mailbox Full bounce, over 8% engaged with a subsequent email in the next 7 days and over 31% engaged with an email over the course of the next 12 months.

As a sender who’s suppressing Mailbox Full bounces after the first occurrence, you could be losing nearly 1/3 of those recipients for no reason. At the least, it’s worth some analysis of your own data (or your ESP’s) — you’ll likely find some room for improvement in how you’re handling these bounces.

For the details — along with our findings on bounces caused by spam, delivery timeouts, and DNS errors — check out the full post.

– BG

Industry Updates

AOL mail seeing Yahoo deferrals as mail integration continues

170403180613-yahoo-aol-oath-780x439A few weeks ago we told you about AOL’s migration of their MX servers to Yahoo’s infrastructure as part of the merger of the two entities under Verizon’s new Oath brand. Since that change in early February, mail to AOL recipients has been handled by Yahoo’s servers. No specifics have been released on how the combined mail system will handle filtering, but observations of recent bounces may shed some light on that.

Over the past 2-3 weeks a number of senders have been seeing the dreaded “Yahoo deferrals” from recipients with AOL email addresses. These deferrals – temporary bounces usually caused by a high complaint rate – occur frequently for many high-volume senders mailing Yahoo recipients. These bounces are typically returned in a format similar to the following:

421 4.7.0 [XXXX] Messages from XX.XX.XX.XX temporarily deferred due to user complaints – X.X.X.X; see https://help.yahoo.com/kb/postmaster/SLN3434.html

The appearance of these types of bounces when sending to AOL recipients means you now have to contend not only with AOL’s spam filtering but with that of Yahoo. While AOL is known for its useful resources and responsive Postmaster team, the Yahoo Mail team can be more difficult to reach when issues arise. If you do run into any of these bounces, it’s probably a good idea to reach out to Yahoo via their Support form since the filtering is occurring on their mail servers.

– BG