Note: these limits apply only to user's mailboxes. Any mail sent via a shared mailbox, a 3rd party service, or a distribution group will be unaffected.
Two types of limits apply on our Exchange tenant:
- Per-Mailbox Recipient Limit: this defines the number of recipients users can include on a single message. The per-mailbox recipient limit is a property of users' mailboxes in Exchange. Users that exceed this number of recipients will receive a non-delivery report and their message will not be sent.
- Daily Recipient Limit: this defines the number of recipients that a user can send to in a 24 hour period. This limit is defined by two anti-spam outbound policies in Exchange, one for students and one for staff. Users that exceed this limit will have their mailbox placed on the Restricted Entities List, and they will be unable to send mail until they are removed.
Outlook Email Limits:
- Per-Mailbox Recipient Limit: 150 for students (500 for staff and faculty)
- Daily Recipient Limit for Students: 150
- Daily recipients for faculty/staff: 1,000
File Attachment Size Limit in Outlook:
- The attachment size limit for files is 25 MB.
- You can also share a file from OneDrive. This way, your recipients can receive larger files and collaborate in real time. The attachment size limit for OneDrive files is 2GB.
Note: For the purposes of the recipient rate limit and the recipient limit, a distribution group that is stored in the organization's shared address book counts as one recipient.
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