A 550 email error is a permanent rejection: the receiving mail server refused your message and will not accept it if you simply resend. The text after the code explains why, and it varies between providers. Reading that text carefully is the fastest way to fix a 550 bounce.
Before you start
- Open the full bounce message and copy the line with
550and the server that sent it. - Check delivery details in cPanel → Email → Track Delivery.
Common 550 errors and what they mean
| Bounce text | Meaning |
|---|---|
| 550 5.1.1 User unknown / No such user | The recipient address does not exist. |
| 550 5.7.1 Relaying denied / Relay not permitted | You sent without authenticating, or DNS sends mail for the domain elsewhere. |
| 550 5.7.1 SPF / DMARC policy | Your domain's SPF or DMARC says this server is not allowed to send for it. |
| 550 … listed / blocked using … | The sending IP is on a blocklist. |
| 550 Sender verify failed | The receiving server could not verify your From address. |
| 550 Message rejected as spam | Content or reputation filters rejected it. |
How to fix 550 errors
- User unknown: check the recipient address for typos, or ask them for the correct one.
- Relaying denied: make sure your mail client uses SMTP authentication (see SMTP authentication failed). If the error comes from your own server for your own domain, check cPanel → Email → Email Routing is set correctly.
- SPF or DMARC failure: in cPanel → Email → Email Deliverability, check SPF and DKIM show as valid and repair them. If you send through other services (newsletters, CRMs), include them in a single SPF record.
- Blocklisted: note the list named in the bounce and contact support with the bounce. On shared hosting we check and request delisting for our IPs; on a VPS, fix the cause (compromised script or account) before requesting removal.
- Sender verify failed: make sure the From address exists and the domain's MX records are valid.
- Rejected as spam: avoid link shorteners, image-only emails and attachments like
.zipor.exe; see emails going to spam.
Warning: If your account suddenly gets many 550 spam bounces you did not send, a mailbox password or website script may be compromised. Change passwords and scan the site right away.
FAQ
Should I resend after a 550 error?
Only after fixing the cause. A 550 is permanent, so resending unchanged will fail again.
What is the difference between 550 and 554?
Both are permanent failures; 554 is a more general "transaction failed", often for spam or policy reasons.
Can I fix a 550 from the recipient's side?
The recipient can whitelist you, but fixing SPF, DKIM and reputation helps with everyone.