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University of Wyoming Division of Information Technology

Handling Large Attachments Before Migration

To prepare for the move to Microsoft's Office 365, individuals need to remove any messages in their mailbox that are larger than 35 MB. If your mailbox includes messages larger than 35 MB, you need to take some action on them. This includes both messages you've received and messages you've sent.

You should review these messages and decide, for each message, whether to

  • save the attachments,
  • delete the attachments but save the message,
  • delete the message (including the attachments), or
  • save the message to local storage.

In nearly all cases, these messages are large because of attached files. You may have already saved these files to disk when you received them. If there are oversized messages in your Sent or Sent Items folders, you probably still have the originals that you sent.

What happens if you don't do anything?
When your mailbox is migrated to Office 365, any oversized messages that remain in your mailbox will be left behind. As a safety net, Information Technology will create a copy of the oversized messages. These copies will be stored in a location accessible only by you. It won't be linked to or available from your Office 365 mailbox, so for convenience, you should plan to handle your oversized messages as outlined above.


Questions, comments, concerns?

Call the IT Help Desk at 307 766-4357, option 1, or email


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