Email Sending Limits for SCSU Office 365 Accounts


The purpose behind reducing sending limits is to help limit the ability of compromised accounts to inflict harm to other user accounts. 


How many emails can I send as an employee, a student, or an alumni?

How many emails can I send via my distribution list?


The following sending limits will be set for Students and Alumni email accounts in the Office 365 Shared Tenant:

  • External hourly limit = 100 
  • Internal hourly limit = 500 
  • Daily limit = 1500 



  • Recipient rate limit = 10,000 recipients per day
  • The recipient limit Customizable up to = 1000 recipients
  • Recipient address limit = 400
  • Message rate limit = 30 messages per minute

Distribution Lists:

  • Daily Limit: 10,000


If you getting blocked from sending, here are some suggestions-

1. Utilized a shared mailbox - (This may already exist. If not, we need to get one created. The shared mailbox should be used to send out mass messages.) The same rules apply to both individual and shared mailboxes, however, sending the message from a shared mailbox protects the individual's mailbox from inadvertently ending up on the block list when the mass mailing is sent out. The individual mailbox would still be able to send/receive while the issue that flagged the shared mailbox is worked out.

2. Distribution Group or ListServ - Which one to move forward with depends on whether or not external addresses are the intended target. Using a distribution list for external entities can be a convoluted mess. Some think a "contact group" within your account that contains all the addresses is the same thing as a listserv. It's not. A contact group in an individual's mailbox counts each recipient individually; a distribution group or a third part listserv counts as one recipient. If the list is maintained is in the user's individual mailbox, they will likely end up on the blocked sender's list again. Using the BCC feature won't alleviate the problem either. All the work to set up a bona fide listserv/distribution group with the desired recipients will take about five minutes and maintenance of the list will be nearly the same time/energy/effort as maintaining a contact group.

3. Scheduled Mail Delivery - If the ListServ will always be changing, it may be best to schedule the delivery of these messages in batches. [] In order to stay clear of Microsoft's sending limits (mentioned above), it would be best to keep the list of recipients in each batch to less than 50, and schedule no more than one delivery per hour. This will allow other mail to continue to flow from the sending mailbox as expected.


Article ID: 127574
Tue 2/9/21 9:01 AM
Mon 11/15/21 2:51 PM

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