Anti-Spoofing Protection & MailChimp

[DMcGehee]

We use MailChimp to send out campaign emails to thousands of people, a lot of which are part of our internal organization.  We have SPF, DKIM set up, and it appears they are passing, but the anti-spoofing protection sends about half of the emails to the Junk folder in our user inboxes.  There doesn't seem to be any consistence to it either.

I have found in the message headers

...compauth=fail reason=601

...CTRY:US;EFV:NLI;SFV:SPM;...

...PTR:mail247.suw121.mcdlv.net;MX:1;A:1;CAT:SPOOF;

What am I missing here?

[#2]

@DMcGehee Hi, did you include MailChimps servers to your SPF record? 

[#3]

@Pavel Otych 

We do have the TXT records in the domain for SPF.  There are no CNAME records for DKIM.  Could that cause this?

TXT	gxxxxxxxn.com	v=spf1 include:servers.mcsv.net include:spf.protection.outlook.com -all	3599
TXT	gxxxxxxxn.com	MS=ms45659264	3599

[#4]

@DMcGehee The record seems to be correct based on MailChimp documentation at https://mailchimp.com/help/set-up-custom-domain-authentication-dkim-and-spf/ Also the mail247.suw121.mcdlv.net (198.2.185.247) is part of the IP range specified at MailChimp servers (198.2.128.0/18) so SPF check shouldn't be failing.

Hard to say really. Try adding the DKIM records + signing, it could help. Also, I suggest you add a DMARC record.  However, there doesn't seem to be much more you can do about it.