Overview
To protect our email environment and maintain a strong sender reputation, Exchange Online enforces anti-spam sending limits for student mailboxes. These limits help prevent compromised accounts, bulk mailing misuse, and accidental spam events.
Different limits apply based on a student’s enrollment status. When limits are exceeded, Exchange Online automatically applies a temporary sending restriction.
Student Sending Limits
Provisional Students
- External recipients: 10 recipients per hour
- Internal recipients: 25 recipients per hour
- Total recipients per day: 50 recipients
Full Students
- External recipients: 25 recipients per hour
- Internal recipients: 50 recipients per hour
- Total recipients per day: 100 recipients
What Counts as a Recipient?
- Each individual recipient counts separately (e.g., one email sent to 10 people counts as 10 recipients)
- Distribution lists count as the expanded number of recipients
- Internal recipients include institutional email addresses
- External recipients include any non-institutional email addresses
Limit Enforcement Behavior
When a student exceeds any of the sending limits, Exchange Online automatically applies the following action:
- Restrict the user from sending mail until the following day
The sending restriction applies to all outgoing email (both internal and external). Incoming email is not affected. The restriction automatically clears the next calendar day and does not require IT intervention.
When sending is restricted, the student may experience one or more of the following:
- Messages remaining in the Outbox
- Non-delivery reports (NDRs) indicating sending is temporarily blocked
- Generic send failure messages in Outlook or Outlook on the web