Is 550 5.7.40 permanent or temporary?

550 5.7.40 is a permanent (5.x.x) failure — the server will not accept the message as-is, and retrying without changing anything won't help. You need to fix the underlying cause.

Is this my problem or the recipient's?

It depends on the cause — no dmarc record was ever published is the most common. Work through the causes below to find which applies to you.

How do I check my sending setup?

Run a free EmailHealth check on your domain — it verifies SPF, DKIM, DMARC, blacklist status, and more in a couple of seconds, which covers the most common causes of delivery failures.

550 5.7.40 — Gmail blocked the message: no valid DMARC record

550 5.7.40 is a permanent SMTP reply meaning gmail blocked the message: no valid dmarc record. Gmail requires bulk senders to publish DMARC for the domain in the From: address. Without a valid record at _dmarc.yourdomain, Gmail rate limits and then blocks the mail.

What 550 5.7.40 means

Gmail requires bulk senders to publish DMARC for the domain in the From: address. Without a valid record at _dmarc.yourdomain, Gmail rate limits and then blocks the mail.

⚠️

This is a 5.x.x permanent failure — the message will keep bouncing until you fix the cause. Retrying the same message unchanged won't help.

Common causes

📨

No DMARC record was ever published

Most common

Many domains have SPF and DKIM but never added the TXT record at _dmarc.

🔁

The record has a syntax error

Common

A missing v=DMARC1 at the start, a wrong tag, or a smart quote copied from a document makes the record invalid.

⚙️

The record is at the wrong name

Less common

Some DNS panels add the domain again, so the record ends up at _dmarc.example.com.example.com.

How to fix 550 5.7.40

1
Publish a starting DMARC record
Add a TXT record at _dmarc with: v=DMARC1; p=none; rua=mailto:you@yourdomain. p=none is enough to meet the rule while you collect reports.
2
Check the record
Run the free DMARC checker. It shows the record Gmail sees and any syntax problem.
3
Move to enforcement later
When reports show all your real mail passes, change p=none to p=quarantine and then p=reject.

Confirm your domain is set up correctly

Most delivery failures — permanent or temporary — trace back to authentication or reputation. Run a free EmailHealth check to confirm SPF, DKIM, DMARC, blacklist status, and TLS are all healthy for your sending domain. If you send in volume, free daily monitoring will alert you before a small issue becomes a flood of bounces.

Gmail blocked the message: no valid DMARC record