Bounce codes › Microsoft 365
550 5.7.124: Sender not in allowed-senders list
You wrote to a group address (a distribution list) that only accepts mail from a fixed list of people. You are not on it.
Only the recipient side can fix it Refused by a rule on the recipient side
You are not on the list of people allowed to write to this group.
- Sent by: Microsoft 365 / Outlook
- Permanent (hard bounce). Sending the same message again fails again.
How Microsoft 365 words it (source):
Sender not in allowed-senders list
Why it happens
- The group owner restricted who may write to it, for example an
all-staff@list. - You are the owner but not on the allowed list. Microsoft notes that even the owner may need to be added.
What to do
- Write to the people directly instead of to the group.
- Ask the group owner or the organisation's email administrator to add you to the allowed senders.
Don't confuse it with
550 5.7.133 is a group that refuses everybody outside its organisation. With 5.7.124 the group has a named list of allowed senders.
Questions
Is the group address invalid?
No, it exists. It just does not take mail from you.
Should it be on a marketing list?
No. A restricted group address will bounce every time. Remove it and write to individuals.
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 5.7.133Sender not authenticated for group (Microsoft 365)