Modified 07 March 2017 by Ian Weatherhogg

Use this tip to find large attachments in Outlook - in preparation for mail migration to Google Apps or just to clean up your inbox.

If you are thinking of migrating your mail to Google Apps, it's useful to bear in mind that many of the migration tools available (including Google Apps Migration for Microsoft Exchange) have an attachment limit of 25MB. If you have attachments larger than this, you will need to find them and move them out of Outlook.

Microsoft Outlook offers an inbuilt tool to help you clean up your mail, useful even if you just want to tidy up your mail or find out the size of your mailbox.

  • In Outlook 2010 click on File and choose Info - then click on the Mailbox Cleanup button (in 2003 and 2007 click on Tools -> Mailbox Cleanup)
  • The box that pops up allows you to check the size of your inbox and search for attachments larger than a defined size - the largest you can add is 9999KB - doing this will search for attachments over 10MB.
  • The search may take a while depending on your inbox size, once complete click on the Size column header to sort by size
  • Check the In Folder column, since deleted items should not be counted
  • From here you have a few choices, do you want to:
  • delete the email and attachment
  • delete the attachment but keep the email
  • keep the email but delete some of the attachments
  • save the attachment(s)
  • To delete the email and attachment, right click on the mail in the results and select Delete
  • To delete the attachment or some attachments, double click the mail in the results to open it up, select the attachment you wish to remove and choose Remove attachment
  • To save an attachment to your hard drive, open up the mail and choose Save As or Save all attachments, then delete attachments as above.

If you have Gmail take a look at this tip on how to find large attachments in Gmail.

Let us know what you think of this tip in the comments below.