During a Mail migration, the migration of an appointment or mail items fails with the error message:
Error:” Failed to write Appointment: MIME content conversion failed” or
Error writing mail (code 2) : ErrorMimeContentInvalid.
This message indicates that Exchange is not able to convert the appointment or the mail to the RFC822 compliant MIME format as requested by the MailStore Server.
The cloudiway platform can’t migrate these mails.
However, it’s possible Outlook is able to fix them. Try exporting and importing affected items using Outlook or forward them to the target email. Outlook or Exchange may be able to correct the invalid MIME content.
If it’s too much “corrupted”, Outlook or OWA won’t even display the invalid MIME content.