Bounce codes › Microsoft 365
550 5.2.122: Recipient's per hour message receive limit exceeded
This Microsoft 365 mailbox received more messages in the last hour, from all senders together, than Microsoft allows. It refuses more until the hour passes.
Wait and try again Recipient is getting too much mail
The recipient got more messages this hour than Microsoft allows.
- Sent by: Microsoft 365 / Outlook
- Permanent (hard bounce) by its code, so your mail system will not retry by itself. The cause passes: a new message later can get through.
How Microsoft 365 words it (source):
Recipient's per hour message receive limit exceeded
Why it happens
- The mailbox is the target of a mail storm, for example a shared address that gets every system alert.
- Someone signed the address up to thousands of newsletters to bury a real message ("email bombing").
What to do
- Try again later. Nothing is wrong with your message.
- If it is urgent, reach the person another way.
- If you run the mailbox: Microsoft has a report called "Mailboxes exceeding receiving limits" that shows who is flooding it.
Don't confuse it with
550 5.2.121 is the limit for one sender to one recipient. With 5.2.122 your own volume may be tiny.
Questions
Should I remove the address?
No. It exists. Remove it only if it keeps bouncing for other reasons.
Is this a hard bounce?
The code starts with 5, so your mail system treats it as final and will not retry. But the cause is temporary: a new message an hour later can get through.
Got a different bounce?
Paste the whole message into the bounce code lookup. It reads the code and the words and tells you whose move it is.
Related codes
550 5.2.121Recipient's per hour message receive limit from specific sender exceeded (Microsoft 365)452 4.2.2The recipient's inbox is out of storage space (Gmail)