How to remove the Onbehalf From the custom FromEmail

This is not addressed at the Appian product level.
Have a look at this google article which provides some detail describing why this is done, and what options you have to address it.

support.google.com/.../1311182

I did not observe an issue with the authentication as you did. For both, new and old configuration the result was pass.
However, I am observing second issue you mentioned. In the new configuration "sender" doesn't match the "from" address.
So I believe that will be the main root cause of this behavior.

Hi Mike,

I'm running into the same issue (on hehalf of). Do you know if there has been a resolution for this?

This is the rule breakdown from the email header. I don't know if this is the same issue you faced.

Rule breakdown below
pts rule name description
---- ---------------------- --------------------------------------------------
0.00 MIME_HTML_ONLY BODY: Message only has text/html MIME parts
0.00 HTML_MESSAGE BODY: HTML included in message
0.01 BSF_SC0_SA_TO_FROM_DOMAIN_MATCH Sender Domain Matches Recipient
Domain

Any insight would be very helpful. Thanks.

Hi Mike,

I'm running into the same issue (on hehalf of). Do you know if there has been a resolution for this?

This is the rule breakdown from the email header. I don't know if this is the same issue you faced.

Rule breakdown below
pts rule name description
---- ---------------------- --------------------------------------------------
0.00 MIME_HTML_ONLY BODY: Message only has text/html MIME parts
0.00 HTML_MESSAGE BODY: HTML included in message
0.01 BSF_SC0_SA_TO_FROM_DOMAIN_MATCH Sender Domain Matches Recipient
Domain

Any insight would be very helpful. Thanks.

We had to have Appian support set our system-internal email addresses to match the domain of the servers.  I suggest you open a support case and describe your use case.

@ Mike Schmitt 

Does your exchange have DKIM? 

I'm not sure what you mean?