Hi Jmadlang,
From your description, I would like to collect the following information:
1. How many users encounter the issue?
2. If all the users who encountered the issue miss the emails during the same time period (3 weeks before cutover migration to 2 days before cutover migration).
Based on my experience, the issue may be related to the email in Exchange 2007. For example, the emails may be corrupted.
Thanks,
Anna Shi
