[Forum] Unauthenticated email addresses used in Contact Form rejected

[sticheno]

Is there a way to hack this so legitimate unauthenticated mail can be sent from the Contact page? Searched but don't even see the issue raised... I likely missed it or my search parameters are faulty. A Yahoo user comes onto our Forum and is having issues registering as example, contacts us using the Forum Contact page, the mail gets sent then rejected so ultimately we receive the rejected mail so we can answer. I understand why this happens and why companies like Yahoo have implemented these changes. Just don't know where the fix can be applied.

Example:

The original message was received at Sat, 6 Feb 2016 05:20:23 -0600
from localhost.localdomain [127.0.0.1]

----- The following addresses had permanent fatal errors -----
<thisisme@my domain.com>
(reason: 550-5.7.1 Unauthenticated email from yahoo.com is not accepted due to domain's)

----- Transcript of session follows -----
... while talking to gmail-smtp-in.l.google.com.:
>>> DATA
<<< 550-5.7.1 Unauthenticated email from yahoo.com is not accepted due to domain's
<<< 550-5.7.1 DMARC policy. Please contact administrator of yahoo.com domain if
<<< 550-5.7.1 this was a legitimate mail. Please visit
<<< 550-5.7.1 https://support.google.com/mail/answer/2451690 to learn about DMARC
<<< 550 5.7.1 initiative. tu10si7951901obb.27 - gsmtp
554 5.0.0 Service unavailable

Final-Recipient: RFC822; [email protected]
Action: failed
Status: 5.7.1
Remote-MTA: DNS; gmail-smtp-in.l.google.com
Diagnostic-Code: SMTP; 550-5.7.1 Unauthenticated email from yahoo.com is not accepted due to domain's
Last-Attempt-Date: Sat, 6 Feb 2016 05:20:24 -0600