On nurturing tracks, when we get those email auto replies...
I guess I know the answer for "email changed" auto replies. Just edit the email on your lead database for that same lead. But does it change on SFDC? Or do i need to change on both?
And what is the best to do for "no longer works here" emails? Unsubscribe the lead if there are no other emails? And if there are other emails like reach out to such firstname.lastname@example.org... what would you do?
Yes, you should mark the lead as Email Invalid=T as well as Status=Gone, INV or something like that.
For a new email address, create a new lead, unless it they are at the same firm still. SFDC will receive all the correct updates.