I am wondering why entire lists would be marked with Marketing Suspended = true. Several of our lists are almost entirely suspended and it seems unlikely that there would be that many addresses with soft bounces. I've talked to the person who uploaded the specific list I'm working with and they did not suspend the whole group. I looked in the activity log for several of these people and there is no indication of when their marketing suspended turned to "true".
I know I can go and unsuspend them all but I want to get to the root of the problem if possible. Thanks!
I don't blame you for wanting to get to the bottom of this - it's not the kind of thing you should ignore! Activity log really is the best place to debug this. Are you sure Filter is set to "none" when you view the activity log?
Alternatively, check your initial import csv doesn't have a column heading named Marketing Suspended with its column cells set to 1, as this would explain why your list would be set to Marketing Suspended on import.
Adam has an excellent point regarding the list import.
It can be a matching field containing 1 (as Adam highlighted) or the field mapping in the import's dialog box.
Please copy/paste the column headers (first line of your CSV) and the first line containing data. It is ok to replace the names and email addreses provided the commas separating the fields remain intact.