Fix "550 5.4.1": The recipient address was rejected (relay or recipient policy)
If your email is bouncing with 550 5.4.1, it means the recipient address was rejected (relay or recipient policy). Here is exactly what causes it and how to fix it.
What 550 5.4.1 means
550 5.4.1 typically means the recipient server will not accept mail for that address from you, often due to relay-access rules, a recipient-side policy, or an address that no longer exists.
How to fix 550 5.4.1
- Verify the recipient address is valid and active.
- Confirm you are not being treated as an open relay or unauthenticated sender.
- Authenticate properly and remove addresses that repeatedly return 5.4.1.
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