IT Connect

Information technology tools and resources at the UW

Limits of Exchange Online

The following capacity limits apply to UW Exchange.

Feature Maximum Comments
Message size 150 MB
Subject length  255 characters
File attachments (per message?)  250
Multipart message  250 parts
Embedded message depth  30 messages
Recipient rate limit  10,000 per day
Message rate  30 per minute
Messages per mailbox folder  1 million
Subfolders per mailbox folder  1000
Folder hierarchy depth  300
Concurrent MAPI connections to a Mailbox 32
Calendars that can be viewed or linked 255
Deleted Items folder retention period  Unlimited Although UW Exchange is currently configured to retain deleted items, do not depend on that configuration for archive or business critical processes.  Microsoft may revert this setting to 30 days or less without notification, resulting in the loss of older data.
Retention period for items removed from the Deleted Items folder  14 days UW Exchange is configured for the default 14-day retention policy.  However as of June 5, 2014, UW-IT is in the process of updating all accounts to use the maximum 30 days allowed. It is important to note that retention of calendar items is always 120 days.
Junk Email folder retention period  120 days Although UW Exchange is currently configured to retain junk items for 120 days, users should not depend on that configuration for archive or business critical processes.  Microsoft may revert this setting to 30 days or less without notification, resulting in the loss of older data.
Mailbox calendar delegates  4 Outlook does not limit the number of delegates that you can add. However, Microsoft recommends that you grant Editor permissions to only one delegate, as described in Best practices when using the Outlook Calendar. You may find acceptable performance for more delegates, but it is common to experience increased numbers of corrupted or inappropriately processed meeting events with increased numbers of delegates.

It is not supported to have a user as both a delegate and full mailbox access.