Tagbounce handling

February 8, 2010

AOL transmitting 4xx error for user unknown

By laura
1 Min read
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08February

AOL is currently returning “451 4.3.0 <invaliduser@aol.com>: Temporary lookup failure” in some cases when they really mean “550 user unknown.” This message from AOL should be treated as 5xx failure and the message should not be retried (if at all possible) and the failure should be counted as a hard bounce for list management purposes. This is something broken at...

February 2, 2010

20% of email doesn't make it to the inbox

By laura
3 Min read
11 comments
02February

Return Path released their global delivery report for the second half of 2009. To put together the report, they look at mail delivery to the Mailbox Monitor accounts at 131 different ISPs for 600,000+ sends. In the US, 20% of the email sent by Mailbox Monitor customers to Return Path seed accounts doesn’t make it to the inbox. In fact, 16% of the email just disappears. I’ve blogged in...

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