Basically the title:
I have a large amount of records in Salesforce that I need to check and see if they exist in marketo. Is there a way to do a lookup on a large number of records (preferably looking at just the email address since that is what matters most) to see if they exit in Marketo?
Any advice would be appreciated.
That's not large.
For a list that small, cut it into blocks of 1000 to be on the safe side, then paste each block into a Smart List filter on Email Address (multi-choice box).
Import your list, any amount lines.
Choose at beginning of the import process "Skip new people and updates"