In this article from Marketo they clearly state the hitting the "Log with Marketo" button in the outlook add-on logs an activity under a lead's activity log: Log Inbound Mail From Your Leads in Marketo - Marketo Docs - Product Docs .
I tired this with an email reply I received from an email blast that was sent via Marketo and it's not appearing in the lead's activity log.
I thought of a few reasons this may be:
Can anyone provide guidance around why this feature isn't working for me?
This has always worked for us - just be sure that you are checking the Activity Log of the lead record of the From email address . I'm fairly certain that reasons 1 - 3 are not applicable, so I would open a case with Marketo tech support, who may be able to provide more insights.