5.7.26 Message fails sender authentication (SPF, DKIM and DMARC)

The message did not pass the sender authentication that the receiver requires, usually a DMARC policy of quarantine or reject on your domain, combined with failing SPF and DKIM alignment.

5.7.26 Message fails sender authentication (SPF, DKIM and DMARC)

Permanent: retrying will not help

The message did not pass the sender authentication that the receiver requires, usually a DMARC policy of quarantine or reject on your domain, combined with failing SPF and DKIM alignment.

Usual causes

Your domain has a DMARC policy, and the message did not pass SPF or DKIM in a way that matches the From address.
You send from a service you have not set up for your domain.

What to do

Set up the sending service for your domain, so its DKIM signature uses your domain.
Check your domain with the SendSend domain checker, and read DMARC reports to find the senders that fail.

Usually the fault of: sender.

Common questions.

What does 5.7.26 mean?

The message did not pass the sender authentication that the receiver requires, usually a DMARC policy of quarantine or reject on your domain, combined with failing SPF and DKIM alignment.

Will retrying fix 5.7.26?

No. It is a permanent failure, so retrying the same message will not help, and repeated attempts can hurt your sending reputation. Fix the cause first.

How do I fix 5.7.26?

Set up the sending service for your domain, so its DKIM signature uses your domain. Check your domain with the SendSend domain checker, and read DMARC reports to find the senders that fail.

Other codes: 5.1.1 · 5.1.2 · 5.1.3 · 5.1.6 · 5.2.1 · 5.2.2 · 5.2.3 · 5.3.4 · Decode a whole bounce message

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