Exchange Online Email delivery

5.2.2: submission quota exceeded (sending limit reached)

Likely causes

• The mailbox sent to more than 10,000 recipients in 24 hours.
• An app or device sent more than 30 messages a minute through the mailbox.
• The account is compromised and is sending spam.
• Other mail systems use 5.2.2 for a full mailbox, so check which server sent the bounce.

How to fix it

1. Look at the bounce. If it came from another company’s server and mentions a full mailbox, the fix is on their side. This page covers the Exchange Online meaning.
2. Check the sender’s Sent Items for mail they didn’t send. If you find any, reset the password and follow Microsoft’s compromised account steps.
3. If the sending was legitimate, wait. Sending resumes once the recipients sent in the last 24 hours drop below the limit.
4. If the mailbox was blocked for spam, an admin must remove it from the Restricted entities page in the Microsoft Defender portal after the account is secured.
5. For newsletters or bulk mail, use a bulk email service instead of a user mailbox.

Checked against: learn.microsoft.com, learn.microsoft.com, learn.microsoft.com