Hard Bounce Smart List - What filter will get me the most accurate data?

Hey Justin, I'd use your existing filters along with the "Email Suspended = True" filter for hard bounces. This Marketo Product Docs article explains a little more about the Email Suspended filter: Hard and Soft Bounces in Email - Marketo Docs - Product Documentation.

I would answer your question, with a question: Do you track your bounces and update the 'email invalid' flag? Marketo's out of the box 'bounce list' in your Lead Database will define bounces as 'email invalid = true' -- but you can manage your bounces outside of that as well. For instance, a trigger that fires on "email bounces" and preferrably a 'min number of times' constraint as well (I flag after 2 bounces) then the flow marks the email as invalid.

There's also a trigger for 'email bounces soft' which you can setup to monitor over a period of time. I use 6 times in the last 90 days as a default.

Overall, if you're managing your 'email invalid' field with bounce data, as described or some other version, then 'email invalid' would be a good enough way to track what you're doing.

Hi Justin,

Normally, "email bounced" should also show in the "email invalid", but the opposite is not true as "email invalid" also include ill-formed email addresses or can also be set manually or through a smart campaign flow step.

Furthermore, some hard bounced might not show in the email invalid or email bounced smart lists. Some error codes might be wrongly interpreted by Marketo as soft bounces, in which case some hard bounces will actually show in the "email soft bounced" filter.

Te following table, borrowed from @Josh Hill​'s Marketo Rockstar Guide, may help you:

It might be worth setting up a smart campaign that flags as invalid some of these 5xx codes that are treated as soft by Marketo and should be classified as hard.

-Greg