Office 365 - What are the limitations for message size, recipient number, and mailbox storage?
The specifications below outline the mailbox storage capacity limits as well as message and recipient size quotas associated with Office 365. Email usage data collected by the Administrative Excellence Phase II team suggest that only a very small percentage of campus users have email capacity needs beyond these limitations.
Important: The limits discussed below are set by Microsoft and cannot be controlled by UW-Madison administrators. For example, if you exceed the sent message daily limit, your account will be blocked from sending any further messages for a period of 24 hours.
Mail size quotas / caps:
|Outlook on the web|
|Outlook 2016 or 2013 **|
|Other desktop clients
(Thunderbird, Apple Mail, etc) ***
*** The Office 365 Technical Team is still in the process of determining whether there will be additional message size limitations for mobile devices. Some mobile clients may impose additional message or attachment size limits. These limitations can vary by device, client or settings selected.
These limits include all attachments, as well as the message itself. If an incoming message larger than 25 MB is sent to Office 365 recipient, the sender will receive a notification that the delivery has failed.
Other limits / caps:
|Max email mailbox storage|
|Max recipients per message|
|Max recipients per day|
|Maximum number of distribution group members|
|Limit sending messages to large distribution groups|
|Maximum message size for large distribution groups|
Review the Microsoft Exchange Online Limits documentation for a more thorough list.
- Office 365 - Frequently Asked Questions (FAQ) by Category
- Office 365 - How will we manage bulk email distribution and instances where systems generate messages that exceed the daily limit of 10,000?
- Office 365 - I often collaborate on documents that are over 25 MB. How do I work around this limitation?
- Office 365 - Get Better Performance when Using Outlook