During a Mail migration, the migration of calendar or mail items fails with the following error message:

Error:”Failed to write Appointment : MIME content conversion failed” or

Error writing mail (code 2) : ErrorMimeContentInvalid.


This message indicates that internal Exchange function is not able to convert an appointment or mail to the RFC822 compliant MIME format as requested by MailStore server.



In some cases you will find such items is corrupted in your source or they represent non mailbox items. You can try to migrate them manually but note that some of mail client (such as Outlook or OWA) even don’t display  an invalid MIME content.

In some rather cases our team is able to repare it so please contact us to, providing one representative example.