5.2.122 Microsoft bounce: recipient hourly receive cap
What 5.2.122 means
The recipient mailbox received more messages per hour from all senders than Exchange Online allows, so new mail is refused for now.
Message text
Recipient's per hour message receive limit exceeded
Common causes of 5.2.122
- Recipient exceeded the per-hour receive limit across all senders, typically during a mail storm
How to fix 5.2.122
- Retry later; the limit applies to the recipient mailbox, not to your domain.
- Reduce the hourly volume that all senders send to that mailbox.
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How to read 5.2.122
The second part, 5.2.122, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 2 is mailbox: a problem with the recipient mailbox, such as full, disabled or unknown. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: learn.microsoft.com. Last verified 2026-10-20.
Related guides
- How to create an SPF record (syntax and examples)
- How DKIM works and how to publish a DKIM record
- How to set up a DMARC record, from p=none to p=reject
Related codes
- 5.2.2 SMTP: mailbox full
- 5.2.3 SMTP: message too large
- 5.2.2 Microsoft: submission quota exceeded
- 5.2.121 Microsoft: per-sender hourly limit
- 550 5.2.1 Gmail: recipient mailbox inactive
- 552 5.2.2 Gmail: inbox full and inactive
FAQ
What does 5.2.122 mean?
The recipient mailbox received more messages per hour from all senders than Exchange Online allows, so new mail is refused for now. This is a permanent failure.
How do I fix 5.2.122?
Retry later; the limit applies to the recipient mailbox, not to your domain. Reduce the hourly volume that all senders send to that mailbox.
Is 5.2.122 permanent, and should I retry?
5.2.122 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.