Bounce codes › Microsoft 365
550 5.1.90: Daily limit for message recipients reached
Microsoft 365 counts how many recipients each mailbox writes to in 24 hours. Your mailbox went over that number, so further messages are refused until the count drops.
Wait and try again You hit your own sending limit
You reached Microsoft’s daily limit for the number of recipients.
- 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):
Your message can't be sent because you've reached your daily limit for message recipients
Why it happens
- You sent a mailing to a long list from a normal mailbox.
- An app or script sends through your mailbox and sent more than usual.
- Your account was hacked and is sending spam. Microsoft names this as a possible cause.
What to do
- Wait. The limit is counted per 24 hours.
- Check Sent Items for messages you did not send. If you find any, change your password at once.
- Split big mailings over several days, or move them to an email service made for bulk sending.
Don't confuse it with
550 5.2.2 Submission quota exceeded is the sister code: it covers the recipient limit and also the limit on messages per minute.
Questions
Are the addresses I wrote to invalid?
No. Nothing was checked on the recipient side. Keep them.
Does each address in To, Cc and Bcc count?
Yes. The limit is on recipients, not on messages.
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 5.2.2Submission quota exceeded (Microsoft 365)550 5.1.8Access denied, bad outbound sender (Microsoft 365)550 5.4.5Daily user sending limit exceeded (Gmail)