Recipients get "unverified" emails with "CAUTION: SUSPECT SENDER" warnings

[user77336]

Hi,

Does anyone have a solution to this issue - see subject?

All our self-authentication is in place and green results. DNS records are all correct. I have been onto Microsoft and they are saying SPF softfail the likely cause. But, CC KB says it is not required which the check will not validate due to sender (ours) and sending system (CCs) both being different domains. I have requested our domain management to add it nonetheless.

MS Support also said to submit an example email into their analysis system in MS Security portal.

Interestingly, it has come back with:

DMARC

Fail

DKIM

Fail

SPF

Soft fail

Composite authentication

Fail

Also, the Sender IP is showing as a Microsoft IP address. Also, the Message Header Analyzer (https://mha.azurewebsites.net) shows this for the Received-SPF:

SoftFail (protection.outlook.com: domain of transitioning in.constantcontact.com discourages use of 104.47.17.108 as permitted sender)

We would just like to get clean messages out to recipients for our events rather than getting blocked inadvertently.

Thanks.

Jason

[William_A]

Hello @user77336 ,

I'd advise reaching out to our Delivery team to see if they'd have any further insight on your specific situation, especially if this warning is showing with actual email sendouts and not un-authenticated test emails.

Beyond that, it'd come down to making sure your authentication is 100% exactly as it needs to be, and satisfies Outlook's expecations. Anyone not using Outlook is unlikely to see such an error message, unless there's an actual issue with how the authentication was setup with your domain. You may need to reach out to OL support, or see if your domain host would have any further insight (if applicable).