Additional follow up after many many hours of going through code on our end and PHPMAILER-PRO... Setting DKIM variables as mentioned IS adding the DKIM-Signature to the outgoing message (using IMAP I should specify) and GMAIL/Google is accepting it and allowing it to go to a GMAIL email address. The email body isn't formatting correctly for the recipient. Basically, for a one line TEXT message, there are multiple lines of actual email header information showing up in the body of the message for the...
DKIM not working and needed possibly for GMAIL recipients