Exchange - Mail sending limits for individuals

Issue/Question

  • What are the mail sending limits in Exchange Online?

Environment

  • Oregon State University
  • Exchange Online

Explanation

Microsoft Exchange Online has the following limits on sending messages:

  • 10,000 recipients per day: A mailbox can send to up to 10,000 recipients in a 24-hour period. If this limit is exceeded, the sender will receive bounce messages when trying to send any mail until the 24-hour period is up.
  • 500 recipients per message: The maximum number of recipients on an individual message is configurable from 0 - 1000 (set to 500 by default)
    • A distribution list counts as one recipient regardless of the number of members, though there are some additional things that have to be in place if the distribution list has more than 5000 members. If those pieces are not in place, the sender will receive a bounce message indicating the distribution list is not ready to accept mail yet, and to contact their administrator.
    • A distribution group (in someone's contacts) counts all the individual members
    • Note that attempting to send to more than 500 recipients in a single message will still count against the 10,000 recipients per day limit, even though the message was not delivered.
  • Message rate limit: The message rate limit is 30 messages per minute. The message rate limit is how fast the message(s) are released when sending - if you queue up a message to 300 recipients it will go out to everyone gradually over the course of 10 minutes (but appear to send instantly on the sender's end).

Resolution

  • Create a Mailman list or Exchange distribution list when you need to send to large numbers of recipients.
  • Break up large mailings into messages with less than 500 recipients each.

 

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Details

Article ID: 29655
Created
Tue 4/25/17 10:01 AM
Modified
Wed 10/21/20 1:46 PM