Mail delivery failed – sign up register and authenticate

I am now receiving a different mail delivery fail message after I speaking with the server:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

?[email protected]
???host?gmail-smtp-in.l.google.com?[173.194.76.26]
???SMTP error from remote mail server after end of data:
???550-5.7.26 Your email has been blocked because the sender is unauthenticated.
???550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
???550-5.7.26
???550-5.7.26 ?Authentication results:
???550-5.7.26 ?DKIM = did not pass
???550-5.7.26 ?SPF [post.day] with ip: [91.109.115.123] = did not pass
???550-5.7.26
???550-5.7.26 ?For instructions on setting up authentication, go to
???550 5.7.26 ?https://support.google.com/mail/answer/81126#authentication?ffacd0b85a97d-37cd56ead3fsi3463367f8f.905 – gsmtp
Reporting-MTA: dns;?lon16.onrocket.com

Action: failed
Final-Recipient: rfc822;[email protected]
Status: 5.0.0
Remote-MTA: dns;?gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 Your email has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
550-5.7.26
550-5.7.26 ?Authentication results:
550-5.7.26 ?DKIM = did not pass
550-5.7.26 ?SPF [post.day] with ip: [91.109.115.123] = did not pass
550-5.7.26
550-5.7.26 ?For instructions on setting up authentication, go to
550 5.7.26 ?https://support.google.com/mail/answer/81126#authentication?ffacd0b85a97d-37cd56ead3fsi3463367f8f.905 – gsmtp

Hi @postday,

Thanks for reaching out, and I apologize for the inconvenience caused!

According to the recent debug log you shared, it appears that your website is trying to send emails without an authenticated email address.

What’s the mailer that you have configured on your site? You can configure a mailer by following this guide. Then, update your “from email address” under the WP Mail SMTP -> Settings page using your authenticated email address, and enable the “force from email” setting as well.

To confirm that you have configured everything correctly, you can send a test email from your site (WP Mail SMTP -> Tools) to the email address displayed on this tool and check your spam score. If you see any issues in that report, please share it with your email provider, and they should be able to assist you in adjusting your SPF, DKIM, and DMARC records.

I hope this helps. Thanks!

Wonderful. Thank you. That has done it.