Does anyone have a definitive list of the types of bounces that cause Marketo to set Email Invalid to True? I was previously under the impression that any hard bounce with a 500-range (e.g. 5xx) bounce code would trigger Email Invalid. However, I can see instances where this isn't the case. The only documentation in the Product Docs I can find on this is woefully short on detail (“Email Invalid - Set to True when a certain type of hard bounce occurs.”).
The question occurred to me because a new client has a smart campaign that sets email invalid to true any time a hard bounce has occurred at least twice in 90 days - and the campaign members I spot-checked had all hard-bounced with 5xx bounce reasons the first time.
It's 550, 551, at least a subset of 553, and 554 that I know of.
It wouldn't be all 5xx errors, because some errors in that range don't indicate the email does not exist. For example, an over-quota-but-still-active (523) or over-size message (552, unlikely with Marketo to be sure, but possible). What are some of the 5xx errors that are not resulting in the system flow action?
Also remember that a seemingly firm 550 doesn't necessarily mean the mailbox can't be reached from outside Marketo (the mailserver being under no obligation to tell you why you aren't allowed to send). And 554 can be because your (the sender's) mail server is misconfigured, i.e. a nonexistent envelope sender. And an address claimed to be "invalid" can become valid over time as spam filters are changed. So the idea that 2 hard bounces in 90 days means the email is nonexistent is overly dramatic, if they're not also figuring in successful deliveries!
P.S. IME, people spend too much time worrying about hard bounces and not enough time resolving DNS-related soft bounces...
Thank you, Sandy! I see what you mean. I spot-checked some of the reasons in this instance and they were:
554 rejecting banned content
550 bl.spamcop.net Blocked
550 [internal] [oob] The message was blocked by the receiver.
Based on those reasons and your comment I don't think they should be marking the emails invalid. Do you agree?
Yes, those don't indicate that the mailboxes themselves are invalid.