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


New Member
Apr 19, 2023
Sometimes, a couple of mails towards GMAIL get discarded. The reason is:

< #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 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?


The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!