Email Spam Tester › Fixes

What a finding means and how to fix it

One page per finding that people paste into a search box after a tool reports it. What the line means, which of its several causes you have, and the change that clears it.

• 550 5.7.26 unauthenticated email

  Gmail's 550 5.7.26 bounce has three versions with different causes. How to tell which one you got and what to change so Gmail accepts the mail.

• 554 5.7.5 Permanent error evaluating DMARC policy

  Why Outlook bounces mail with 554 5.7.5 permanent error evaluating DMARC policy, how to find what is broken in the record, and how to check the fix.

• "Be careful with this message" in Gmail

  Why Gmail puts "Be careful with this message" on your email, which of the reasons applies, and what the sender changes so the banner stops.

• DKIM fail

  What dkim=fail means in the headers: "body hash did not verify", "signature did not verify" or "no key for signature", and the fix for each.

• DMARC fail

  Why DMARC fails even when SPF and DKIM pass, how to read dmarc=fail in the headers, and the fix per sending service, Mimecast's "DMARC Fail" included.

• DMARC policy not enabled

  What "DMARC policy not enabled" and "Quarantine/Reject policy not enabled" mean, the record to publish, where it goes, and when to tighten it.

• Email spoofing your domain

  Your real mail flagged as spoofed, strangers sending as your domain, or mail that seems to come from yourself: how to tell which it is and stop each.

• List-Unsubscribe header and one-click unsubscribe

  The List-Unsubscribe and List-Unsubscribe-Post headers Gmail and Yahoo require, what one-click needs to work and why the button may not appear.

• Mail Delivery Subsystem bounce

  What a "Mail Delivery Subsystem" email means: how to read the bounce, what to do about bounces for mail you never sent, and how to spot the scam.

• Multiple SPF records

  Why a domain may publish only one SPF record, how a second one appears, and how to merge them into a single record that covers every sender.

• SMTP error 550 5.7.1

  550 5.7.1 and 554 5.7.1 cover many unrelated refusals. Read the text after the code to tell blocklist, content, DMARC, relay or policy apart.

• SPF softfail

  What spf=softfail and "domain of transitioning does not designate as permitted sender" mean, softfail versus hardfail, and how to make it pass.

• SPF permerror: too many DNS lookups

  Why an SPF record over ten DNS lookups returns permerror, how includes are counted, the void lookup limit, and how to get under ten safely.

• "This message seems dangerous" in Gmail

  Why Gmail puts a red "This message seems dangerous" banner on a legitimate email, what in the message usually causes it, and what the sender can change.

• "We can't verify that this email came from the sender" in Outlook

  Why Outlook says "We can't verify that this email came from the sender", shows a question mark or a "via" tag, and what the sender changes.