Email Sending Limits
Students, faculty, and staff have limits to how many emails they can send in Microsoft 365 per hour and per day. These limits exist to prevent spam, protect server performance, and maintain compliance with anti-abuse policies.
Sending Limits
Affiliation | Internal Limit (hourly) | External Limit (hourly) | Limit (daily) |
|---|---|---|---|
Faculty and Staff | 10,000 | 1,000 | 10,000 |
Students | 500 | 500 | 10,000 |
Emails sent from @uconn.edu to @uconn.edu are considered internal. All others are external.
The daily limit is a rolling 24-hour window.
Each recipient counts as one email.
Sending 1 email to 500 people = 500 emails (because there are 500 recipients).
Sending 500 separate emails to 1 person = 500 emails (because there are 500 sends).
Emails sent from shared mailboxes are subject to the sending limit of the individual sending the message. If a student sends email from a shared mailbox, they will be limited to 500 recipients. If a faculty or staff member sends email from a shared mailbox, it will have the higher limit.
Additional Limits Set by Email Service Providers and Platforms
Microsoft enforces additional sending limits, which are explained here: https://learn.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#sending-limits-1
Outlook won’t let you send an email to more than 1,000 people at a time. If you have more than 1,000 recipients, you need to send the message in batches.
Bulk Mail Solutions
If you need to send more than the hourly limit of emails for your affiliation, ITS offers multiple options:
Listserv: https://kb.uconn.edu/space/IKB/10726900313/Listserv
Mass Mail: https://kb.uconn.edu/space/IKB/10731880527/What+is+the+Mass+Mail+Service%3F
Sending Surveys: To send research surveys, the optimal solution is to use Qualtrics to create and send your survey. Qualtrics has an integrated Mass Mail account specifically to send surveys to large groups.