Resolved Onyx, Google-Mail-error

[Martin_Sauer]

Situation: Plesk onyx 17.8.11 on CentOS Linux 7.6.1810
Server usage: web hosting only, no DNS (DNS is hosted externally), no local mail boxes, server sends emails (from hosted webapps, Plesk, system,..)

This leads to errors with Google Mail:
Diagnostic-Code: smtp; 550-5.7.1 This message does not have authentication
information or fails to pass 550-5.7.1 authentication checks. To best
protect our users from spam, the 550-5.7.1 message has been blocked. Please
visit 550-5.7.1
Bulk Senders Guidelines - Gmail Help for more 550
5.7.1 information.

SPF, DKIM, DMARC require also DNS settings - so the current support-articles dont apply. Also maybe necessary DNS changes cant be reviewed on the server since bind is not installed.

I am aware I can install bind and configure mail completely, yet this sounds like a lot for a "simple" mail server solution.

Any tipps, recommendations, ideas?

 

[Martin_Sauer]

It seems there are two basic solutions to this issue:
- long-time solution: really enable and run own mail, DNS,... on Plesk with SPF,... This also adds the option to fully configure DMARC,.. which additionally improves on domain reputation.
- SPF-only: Google Mail basically checks if there is a fitting SPF-record present. By simply adding DNS-txt-Record of: "v=SPF1 A MX -any" in the domain, which uses the server also as web-server, the issue is gone. "v=SPF1" declares that it is a SPF1 record, "A" declares that all server with DNS A records in the current domain are also allowed to send mails, same with "MX", which declares all servers with a MX record to be authorized to send mail. "-all" finishes the SP! queue declaring that all other E-Mails sent with this domain from other servers shall result in a hardfail (usually deletion without notice).