in doing a on premise exchange to Office 365 hosted exchange I setup the Office 365 environment and then forwarded the on premise inbound email to both on premise and O365 boxes until time of conversion, about 5 days. Then I proceeded to go ahead and export the on premise email. Then when it was time for conversion, I did another export with a date range getting the week that I was forwarding. The reason I did this was to get the email that was replied to, read, or otherwise dealt with during the 5 days of forwarding.
So now that the conversion is done, I connect to the O365 mailbox and then import that 5 days of email, choosing to replace duplicate items. My assumption was that if an email had been read and replied to, the import would over write the unread version that had been forwarded and import the sent one in sent items.
It did import the emails but it duplicated them - I had a ton of emails that were read and then unread - exact emails.
is there a way to import these and over write the unread one in the inbox?