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Size Limits for Microsoft 365 (Outlook) Accounts (Faculty/Staff)

This article applies to: Microsoft Outlook

Mailbox Size Limits

All faculty/staff Office 365 accounts have 100 GB of mailbox storage. The vendor does not accept requests for larger mailboxes.

How Full is My Mailbox?

You can check how much space is left in your Outlook mailbox (whether you use Outlook for Windows or Outlook for Mac) with Outlook on the web.

  1. Log in to Outlook on the web.
  2. Select the gear icon (Settings) at the top right of the window.
  3. From the Settings menu, select Account from the left side of the menu, then Storage from the menu to the right.

Attachment Limits

Attachments are limited to a total of 25MB per message. 

The process of attaching a file to an email increases the size of the attachment. If your attachment is almost 25MB, it may not successfully attach. See our Attachments Not Getting Through article for ways to work around this limitation.

Email Sending Limits

A message can be addressed to a maximum of 300 addresses (To, Cc, and Bcc combined). 

Learn more about how to send mass emails if you need to reach a broader audience.

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