A migrated user (Exchange) send a invitation to a non-migrated user (Notes). In Notes there is a feature called "Request information". When the Notes user uses this feature an email is sent to the Exchange user (organiser)
The email to the organiser shows the wrong sender, not the Notes user, but the Exchange user (organizer)
Sending a "Request Information" request to the host of a Notes originated Calendar invite does not
This is caused by an incompatibility between Notes and Outlook. The Request Information message type is not supported by CMN at this time.
This issue can be resolved in a couple of ways:
1) Modify the Mail template to remove the Request Information button and functionality
2) Advise the Notes user community that this functionality will no longer work when addressing Exchange users.