Resolved Undelivered Mail Returned to Sender when sending to gmail

[Ddungu]

Server operating system version

Ubuntu 20.04.6 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.50

host gmail-smtp-in.l.google.com[74.125.133.27] said:
550-5.7.26 Unauthenticated email from example.com is not accepted
due 550-5.7.26 to domain's DMARC policy. Please contact the administrator
of 550-5.7.26 example.com domain if this was a legitimate mail.
Please 550-5.7.26 visit 550-5.7.26
Control unauthenticated mail from your domain - Gmail Help to learn about the 550
5.7.26 DMARC initiative.
h12-20020a05600c2cac00b003dd1bd06ad3si15743962wmc.70 - gsmtp (in reply to
end of DATA command)

 

[Peter Debik]

Please add a valid DMARC record to your DNS of the domain from where you are sending.

 

[Ddungu]

Thank you for your support finally resolved it by following this link.

 

[Peter Debik]

I wonder how too many database connections could have an influence on DMARC record evaluation at Gmail???