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Guidelines For Cleaning Out Your Mailbox

In 2023, businesses and consumers worldwide sent and received approximately 347.3 billion emails per day.  Typical users will receive 100 to 120 emails per day.  If these emails are not managed promptly, you can inadvertently end up with thousands upon thousands of unnecessary emails.  While keeping email too long may not seem like a bad thing, it does expose you and the University to greater risk.  The threat of data breaches, exposure to data privacy violations and fines, and failure to comply with University Retention Authorizations are all reasons to maintain control of your mailbox.  You should delete all out-of-date and irrelevant messages. Please take the steps below to reduce the size of your Outlook mailbox:

  1. Delete messages that have met their records retention requirements and all non-record messages that are no longer current or relevant. For information on the retention requirements for specific records, see the Records Retention Authorizations at: RECORDS RETENTION AUTHORIZATIONS | University of Missouri System (

    Messages that are not records and can be deleted when they are no longer useful include:

    1. Resource material - material created or received for personal reference purposes.
    2. General routine department business correspondence – messages that have short-term administrative or operation value used to provide information or for the completion of a request or action such as:
      1. routine requests for information
      2. meeting notices and reminders
      3. administrative notices
      4. invitations and responses
      5. interoffice activities
      6. Emails that notify you of meeting acceptances and reminders
      7. "Out of Office" replies
    3. Draft documents
    4. Courtesy copy informational messages – messages you receive to keep you informed on a matter, but you do not need to act on.
  2. Attachments, particularly the larger ones, can take up large amounts of storage in Outlook. Sort your messages by attachment size, and take the following steps:
    1. Delete all messages with attachments that are no longer needed or do not contain records.
    2. Highly restrictive DCL4 data, as defined in the UM Data Classification System, shall not be stored in a University email account. Email messages and/or attachments containing DCL4 data must be deleted or moved to an appropriate storage location as soon as possible but no later than 30 days of receipt or transmission.
    3. If the content of the email message is not needed to complete the record, move the attachments to the appropriate folder on your network or hard drive; then delete the original message from Outlook.
    4. If the email message has additional information, and/or the recipients of the message, or the date and time the message was sent are important; then keep the email and the attachment in your mailbox. Keep only the message with the final version of the attachment in your mailbox.  
  3. If you have multiple messages on the same topic with the same subject (message thread), delete all of the messages except for the final message which contains all of the previous messages.  This can also be achieved automatically across all mailboxes by utilizing Microsoft Outlook's "Clean Up Folder Tool". 
  4. Forward all personal messages and photographs/attachments to your personal email account, then delete the originals from Outlook. 
  5. Set the delete folder to empty when you exit Outlook.
  6. Move email records out of the “Sent Items” folder into appropriate folders and delete all remaining messages.
  7. Complete or delete messages in the “Drafts” folder.
  8. Delete messages in the “Junk E-mail” folder.
  9. See Top 10 Non-Records to Delete or Destroy for additional information.  

Reviewed 2023-11-29