The storage quota for active faculty, students, and staff on the Microsoft 365 Email service is 100 gigabytes (~100,000 megabytes).

This quota represents the maximum storage space allowed for your mailbox on the service. The quota allowance includes the space required to store all email, email attachments, calendar data, contact information, and task management data on the server. This quota only pertains to SERVER storage; local email storage is NOT included in the quota. Local storage is limited only by your computer's disk space and the limitation imposed by Microsoft Outlook.

View step-by-step instructions to check your mailbox size.

How many messages can you store?

• Several factors determine the total number of messages you can store. These include the size of the message body and the size of attachments linked within the messages.
• As a general rule, most email messages don't take up much space. For example, a 20-megabyte inbox may contain 551 messages. If each of the messages included a 2-megabyte attachment, the size of the inbox would swell to a size that exceeds 1 gigabyte. However, to put things in perspective, a three-page Word document that contains text and a picture or two, is usually under 1/3-megabyte, so even if all of the messages came with a three-page Word document, you would still be well within the quota.

Managing the size of your mailbox to remain within the quota.

• There are several things you can do to reduce the amount of storage you are using on the server. You can reduce the size of your mailbox by:
  • Moving messages from the Sent Items folder on the server to a local Sent Items folder in Outlook (Office 365 Email keeps a copy of everything you send in the Sent Items folder - contributing to the total mailbox size)
  • Deleting items in your Sent Items folder if you no longer need them
  • Emptying items from your Deleted Items and Junk E-Mail folders that you no longer need
  • Archive mail that is not needed frequently
    
    • If you find that archiving your email is not reducing the size of your mailbox enough, you can contact the ITS Help Desk and request to have the auto-expanding archive enabled for your account.

Attachment/message sizes

• Individual message size is limited institutionally to a maximum of 150MB.
  • Please note: Attachments, text in the body of the message, and header information, all contribute to the total size of a message.

Folder sizes and the number of messages

• The quota is not based on the number of messages, but rather, it's based on the space that the sum of all of your messages occupy on the server. However, please note: Microsoft recommends limiting the number of messages in an individual folder to 100,000 or less for maximum reliability. Microsoft has identified high item counts in the following critical path folders that cause the most impact on email app performance: Calendar, Contacts, Inbox, and Sent Items.
• ITS has tested various email apps and recommends limiting the number of messages in the Inbox to a maximum of 10,000 messages and all other critical path folders (Calendar, Contacts, and Sent Items) to a maximum of 100,000 messages. Individual folders that exceed the 100,000 message limit may experience performance issues when this number is reached or exceeded.