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.