Office 365 Message & 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

An image of message limits.

 

  • These limits are applied to every email message.

2.) Recipient and sender limits

Limit Students Faculty and staff

  • Maximum recipients per message

(Combined total of To:, Cc:, and Bcc: fields)

500

500

  • Allowed external recipients per hour

500

500

  • Allowed internal recipients per hour

500

1,000

  • Total recipients (internal and external) per day

500

5,000

  • Messages sent per minute

30

30

  • Automatic forwarding to external addresses

Not allowed

Not allowed

  • What happens when the sending limit is reached

The account is blocked from sending email

The account is blocked from sending email

These limits help prevent spam and mass-mailing viruses by controlling messages, senders, and recipients.

Note: Distribution groups in the shared Global Address Book count as one recipient.

Personal Contact groups in a mailbox’s Contacts folder count each member separately.

3.) Retention limits

An image of retention limits.

  • These limits control the amount of time that items in specific folders in the Inbox are accessible.

4.) Distribution group limits

An image of distribution group limits.

  • These limits apply to distribution groups.

5.) Transport rule limits

An image of transport rule limits.

  • These limits control organization-wide rules, als known as transport rules.

6.) Moderation limits

An image of moderation limits.

  • These limits control moderation settings used for message approval applied to distribution groups and transport rules.

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