Gmail rejecting some of our mails because of SPF and DKIM. I have both set up on my Proxmox MG

[StaticOne123]

Sometimes, a couple of mails towards GMAIL get discarded. The reason is:

<gmail-smtp-in.l.google.com #5.7.26 smtp; 550-5.7.26 This mail is unauthenticated, which poses a security risk to the 550-5.7.26 sender and Gmail users, and has been blocked. The sender must 550-5.7.26 authenticate with at least one of SPF or DKIM. For this message, 550-5.7.26 DKIM checks did not pass and SPF check for [domain] did not pass 550-5.7.26 with ip: [xxxxxxxx]. The sender should visit 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for 550 5.7.26 instructions on setting up authentication. f8-20020a05600c4e8800b003f812b84978si7192158wmq.99 - gsmtp>'

I checked on MXtoolbox, and SPF and DKIM work properly..

On Google Postmaster tool, i can see that for a couple of days in this month gmail didnt recognize our SPF and DKIM, now it says it's ok, but some mails still get rejected. About 3 out of 100 mails to gmail get rejected.

What could be the reason?
Anyone had something similar happen?
Thanks..

 

[supermicro_server]

try to configure also the DMARC

 

[kentur]

try to configure also the DMARC

And add the 'rua' setting, so you get all the reports, this way you can see what's wrong a bit easier.

(I know it makes sense to use 'ruf', but google ignores it, so rua is the only option, and can be deleted after troubleshoot is done)