How to Fix a 550 Email Error
A 550 error means the receiving server permanently refused the message and will not retry. The sub-code names the cause: 5.1.1 or 5.2.2 points to the mailbox, 5.7.1 or 5.7.26 to policy or missing SPF and DKIM, a blocklist or missing PTR to the sending IP. Fix that item, then send one test.
For Indian businesses whose outbound mail bounces and who need to fix the exact cause once, not resend blindly.
knowledge
- Read time
- 5 min
- Sections
- 7
- Updated
- 14 Nov 2026
- Written by
- WebJi® team
Last editorial update: 15 November 2026.
What does a 550 email error mean?
A 550 email error is a permanent SMTP refusal: the receiving server has decided not to deliver the message and will not queue a retry the way a 4xx temporary failure does. The digits after 550 — such as 5.1.1 or 5.7.1 — name the family of cause, and the human sentence on that same line names the exact check to change.
A 550 is not a verdict on your whole domain. It is one receiver's answer to one message. Resending the same copy never clears it; fixing the named item does.
| 550 line | What it means | What you change |
|---|---|---|
| 5.1.1 / mailbox unavailable | That recipient address is not a mailbox | Retype the address; do not keep resending |
| 5.2.2 / quota exceeded | The mailbox is full | The recipient frees space or the quota rises |
| 5.7.1 | A policy refused it: SPF, size, content or relay | Fix the check named in the sentence |
| 5.7.26 | The From domain had no passing SPF or DKIM | One SPF record, DKIM on, then one test |
| 5.4.1 | The next host did not answer, or recipient denied | Confirm the domain's MX, then send one test |
| 5.4.5 | The daily sending quota is spent | Stop; send again in the next window |
| blocked | A receiving gateway refused the sender | Check blocklists, then ask their mail admin |
| relay denied | The SMTP server does not accept your login | Authenticate to the mailbox host on port 587 |
One confusion to rule out first: an FTP 550 is a file-permission refusal on an upload, a completely different protocol with the same number. And if the bounce you hold is about SMTP at all, read on.
How do you read the full 550 bounce before changing anything?
Open the non-delivery report and copy three fields from the SMTP reply at the bottom — the 550 plus its x.y.z code, the remote host name, and the sentence after the code — then change only the family that sentence names. The subject line of the bounce tells you nothing.
- 5.4.1 is routing or recipient policy: confirm the domain still has MX records before you touch SPF.
- 5.4.5 means the day's send quota is spent, so you wait — no DNS edit helps.
- A header-syntax 550 means you retype the To address and do not resend the same draft.
Make one change, then send one test to an address you control. If the new bounce shows a different code, undo and work on that one instead.
How do you fix a 550 for a bad address or a full mailbox?
A 550 5.1.1 means the address does not exist there, and a 550 5.2.2 means the mailbox exists but cannot store more mail — in both cases the fix is on the recipient side, not in your DNS.
If the text says "user unknown" or "mailbox unavailable", compare the address character by character with a message that arrived before. Do not trust the mail app's autocomplete — it remembers dead addresses for years. The fix worked when a fresh test to the retyped address is accepted.
If the text says "quota" or "mailbox full", the recipient must delete mail or the host must raise the quota; resending does not create space. The same 550 5.2.2 hits mail sent to your own full mailbox, so keep each box under its limit.
How do you fix a 550 5.7.1 or 5.7.26 policy rejection?
A 550 5.7.1 means the receiving server applied a policy — SPF failure, message size, content filter or relay refusal — and you fix exactly the check the sentence names. For size, send a smaller file; for a content filter, remove the named link or attachment, then send one test.
Gmail's 550 5.7.26 specifically means the From domain was not authenticated. Publish one SPF record listing only the servers allowed to send for that domain — a second SPF record makes both fail — turn on DKIM in the mail panel, and add DMARC at p=none while you read the reports. In cPanel, Email Deliverability shows whether SPF and DKIM are valid. Wait out the DNS TTL before judging the test.
"Relay denied" is a login problem, not a DNS one: your mail app is using an SMTP server that does not know the account. Set the outgoing server to the host that stores the mailbox, switch on SMTP authentication, and use port 587 with TLS. The username is the full email address. It worked when one test leaves the outbox and does not come back as 550.
How do you fix a 550 caused by missing reverse DNS?
Some receivers reject mail when the sending IP has no PTR record, or the PTR name does not match the hostname in the SMTP banner — the bounce then mentions reverse DNS, PTR or a hostname mismatch. On shared mail you cannot edit that PTR from the domain's DNS panel; it belongs to whoever owns the IP.
Ask the host to set the PTR to the exact mail hostname, and make sure the A record for that hostname points back at the same IP. For a WebJi® mailbox, send that hostname to support@webji.services. The PTR record guide shows the lookup. It worked when a lookup of the IP returns that hostname and a new test is accepted.
How do you fix a 550 from a blacklisted sending IP?
If the bounce names a blocklist or says "blocked", a gateway refused the sending IP or domain — the recipient address can still be perfectly valid. Look up the sending IP on the blacklist checker before you touch SPF again.
Stop the cause first — a compromised mailbox, a forwarding loop that passes spam, or a bulk send from a cold IP. Then use that list's own removal form. Delisting is not instant, and a shared IP can be listed because of another account entirely. Do not keep sending from that IP while the listing is open; more volume hardens the listing. The full process is in email blacklist check and removal.
How do you prevent the next 550 on a business mailbox?
Six setup checks remove the usual 550 families, and each is a one-time configuration step rather than another resend of the failed message.
- Publish one SPF record, turn on DKIM, and add DMARC at
p=none; cPanel's Email Deliverability writes the records and flags failures. - Ask the host for a PTR matching the mail hostname, with the A record pointing at that IP.
- Check the sending IP on a blocklist once a month, and again after any spam incident.
- Keep every mailbox under its quota so inbound mail is never refused with 550 5.2.2.
- Warm a new sending IP slowly — do not mail a large list from a mailbox opened the same day.
- Send through the authenticated SMTP of the mailbox host; business email hosting with outbound abuse checks keeps a shared IP cleaner than an open relay ever will.
The setup worked when a test to an outside mailbox arrives and generates no new bounce.
Frequently asked questions
How do I fix error 550 in Outlook or Gmail?
Open the bounce and copy the 550 line — in Gmail it sits inside the failure message, in Outlook inside the non-delivery report. If it says relaying denied, set the outgoing server to the host that stores the mailbox, enable SMTP authentication, and use port 587 with TLS. Then send one test.
Why are my emails bouncing with 550?
The receiver rejected the message for a permanent reason: a bad address, a full mailbox, a failed SPF or DKIM check, a missing PTR, a blocklist, a relay refusal, or a spent daily quota. The sub-code picks which one. Resending the same copy never clears a 550.
What does a 550 blocked email mean?
Blocked means a filter on the receiving side refused the sender or the recipient, and the address may still exist. Check the sending IP on a blocklist, confirm SPF and DKIM pass, and if both are clean, ask the recipient's mail admin whether their gateway is holding your domain.
How do I fix 550 5.7.26 for an unauthenticated sender?
Gmail returns 550 5.7.26 when the From domain has no passing SPF or DKIM. Publish one SPF record covering the servers that really send for you, enable DKIM in the mail panel, and wait for DNS TTLs to expire. A second SPF record makes both fail. Send one test after the change.
Does a full mailbox cause 550 errors?
Yes — a full mailbox typically returns 550 5.2.2 or a line saying quota exceeded. The recipient must delete mail or the host must raise the quota; sending again from your side does not free their space. Mail into your own full mailbox fails the same way.
Last editorial update: 15 November 2026.
Ready to get started with WebJi®?
Join 12,000+ businesses across India and overseas. INR pricing, 18% GST shown before payment and 24/7 email support in Hindi and English — average first reply under 60 minutes.