Below are some of the limits for Office 365 accounts - more detailed information can be found at Exchange Online Limits  

Starting Monday, February 5, 2018, both Office 365 and UI Healthcare email systems increased the maximum message send/receive limits to 150mb.  This change is being made to allow easier collaboration within the University of Iowa.   Please keep the following in mind:

  • Maximum total message send/receive size is 150mb. This includes both the message content and attachments.
  • Attaching a large file to an email message requires uploading that file to the email system. This can increase the time required to send the message.
  • Email attachments count against overall email storage quota.
  • While the UI email systems allow sending and receiving 150mb email messages (including attachments), other external email systems continue to have smaller limits. Some common receiving limits are:
    • Gmail – 50mb
    • – 50mb
    • Yahoo – 25mb
    • Peer universities – varies
  • Whenever possible, it is advised to use a file collaboration tool for large files. The University of Iowa supports Microsoft OneDrive for Business which allows for file sizes larger than 150mb.
Message send/receive size limit (including attachments) -  Keep in mind that someone's mailbox on the Office 365 server will be prohibited from receiving messages if they exceed their maximum quota limit.   Note:  when you attach a file to a message, the file size of the attachment increases (it can increase as much as 30% in size when it is sent).   150 MB 150 MB 150 MB
Address List Limit 1000 1000 1000
Storage - User Mailbox, Shared Mailbox, Resource Mailbox 50 GB 50 GB 50 GB
Recipient Limit per message 500 500 500

NOTE:  Microsoft has implemented Receiving and Sending Limits.  They have stated that Office 365 is not meant to be a bulk email service. "Exchange Online customers who need to send legitimate bulk commercial email (for example, customer newsletters) should use third-party providers that specialize in these services." 


Quota Alerts Across Office 365:

Warning: 49GB 

Prohibit Send: 49.5 GB 

Prohibit Send/Receive: 50GB

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Last updated: 
December 23, 2020