In certain circumstances, Notes Migrator for Exchange may interpret MIME anomalies in the body of a Notes email message to be an attachment and will create and add this new attachment to the migrated message in Exchange. The "Date Modified" attribute of the migrated message may change in Exchange due to this new attachment being added to the message during migration.
This issue was caused by MIME body properties of the original email message in Notes. In this case we found that if we opened the effected message in Notes, pressed Control - A on the keyboard to select all elements in the message body, then pasted the contents into a new message, the new message migrated correctly without an additional attachment in Exchange.
Enhancement request TFS228008 has been submitted to Development for consideration in a future release of Notes Migrator for Exchange.
For additional status updates or information on this please contact your account manager and reference the Change Request # TFS228008.