5.1.90 Microsoft bounce: daily recipient limit hit
What 5.1.90 means
Your account has reached its daily limit on message recipients, so Exchange Online will not submit more mail today.
Message text
Your message can't be sent because you've reached your daily limit for message recipients
Common causes of 5.1.90
- Sender exceeded the recipient rate limit described in the Exchange Online sending limits
How to fix 5.1.90
- Spread the sending over several days or split it into smaller batches within the sending limits.
- If you did not send these messages, the account may be compromised; reset its credentials.
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How to read 5.1.90
The second part, 5.1.90, 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 1 is addressing: a problem with the recipient or sender address. 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 set up MX records (priorities, null MX, migration)
- MX host does not resolve: causes and how to fix it
- Null MX (RFC 7505): publish it for domains with no mail
Related codes
- 5.1.1 SMTP: bad destination mailbox
- 5.1.2 SMTP: bad destination system
- 5.1.3 SMTP: bad address syntax
- 5.1.10 SMTP: recipient has null MX
- 550 5.1.1 Microsoft: bad mailbox address
- 550 5.1.10 Microsoft: recipient not found
FAQ
What does 5.1.90 mean?
Your account has reached its daily limit on message recipients, so Exchange Online will not submit more mail today. This is a permanent failure.
How do I fix 5.1.90?
Spread the sending over several days or split it into smaller batches within the sending limits. If you did not send these messages, the account may be compromised; reset its credentials.
Is 5.1.90 permanent, and should I retry?
5.1.90 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.