Microsoft 365 Message and Recipient Limits*

When it comes to sending messages through Microsoft 365, you may have some questions that directly affect your email experience:

  • Are any sending size limits applied to email messages?
  • What recipient limits are applied to email messages?

The limits on messages, mailboxes, recipients, and email clients fall into one of the following categories:

  • Message limits
  • Recipient and sender limits
  • Retention limits
  • Distribution group limits
  • Transport rule limits
  • Moderation limits
Important - Please be aware of the following:
  • The limits applied to your domain may differ depending on how long your domain has been enrolled in the service. When a limit is changed in the Microsoft datacenters, it can take some time to apply the change to all existing customers.
  • You can't modify most of these limits, but you should be aware of them.
  • These limits apply to both internal and external recipients.

1.) Message limits

2.) Recipient and sender limits

3.) Retention limits

4.) Distribution group limits

5.) Transport rule limits

6.) Moderation limits


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