Email Invalid Program

Are the two fields not connected?

Flow:

Smart List: Trigger: Data Value Changes IS "SFDC Invalid" New Value=TRUE
Flow: Change Data Value IS Email Invalid = TRUE

The flow that Josh has outlined is correct, and it's also correct that the Marketo Email Invalid field cannot be mapped to SFDC. We have set ours up so that it is only a unidirectional (Marketo to SFDC) sync, as I didn't want anyone else telling Marketo whether an email address was invalid -- it isn't always used the way you want it to be used. 

Also, in case you don't already have one set up, be sure to have an email invalid "uncheck" campaign for if the email address is updated. Otherwise, even if someone puts a new or corrected email address in, the person still won't be emailed.

I don't believe that SFDC has a field like this natively, just the opt-out check box. You will need to create a custom field on the lead and contact records in SFDC, map them together and then create the flow that Josh outlines. Replace "SFDC Invalid" with whatever field you created in SFDC. You may want to add a campaign that updates the check boxes if the email is updated to be valid.

To my knowledge, you can't map a field from Marketo to SFDC. If you are creating new fields that need to exist in SFDC, it has to be done in SFDC first and then it will get pulled in by Marketo.

Ok so I took Josh's advice and did:

Smart List: Data Value Changes: Email Invalid (L) New Value: True
Flow: Change Data Value: Email Invalid New Value: True

And it looks like it worked! I'll do the opposite now for if someone un-checks the box.