550 5.4.1: Recipient address rejected: access denied
Microsoft 365 refused the address. Usually the mailbox doesn't exist in that organization, and the organization has set Microsoft to reject unknown addresses.
Hard bounce The address is bad. Don't keep sending to it.
What the bounce message looks like
The wording changes from one provider to another. These are typical examples:
550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (Microsoft 365)Common causes
- A typo in the address
- The mailbox was deleted
- The domain is set up in Microsoft 365 but the recipient isn't
How to fix it if you sent the email
- Check the address. If it's right, ask the person for another way to reach them.
- Remove it from your list if it keeps bouncing.
If you manage the receiving or sending mail system
- Confirm the recipient exists in Microsoft 365.
- If mail for some users is hosted elsewhere, set the domain to "internal relay" in Exchange.
Free tool: paste the full bounce into the bounce message decoder to get a plain-English reading of every code in it.
Questions people ask
- What does 550 5.4.1 mean?
- Microsoft 365 refused the address. Usually the mailbox doesn't exist in that organization, and the organization has set Microsoft to reject unknown addresses.
- Is 550 5.4.1 a hard or soft bounce?
- Hard bounce. The address is bad. Don't keep sending to it.
- Should I remove the address after a 5.4.1 bounce?
- Yes. Remove it from your list, or confirm a new address with the person first.