Print-At-Home sent via Gmail?

Hi all. Anyone out there currently sending print-at-home tickets via G-suite/gmail and willing to let us ask some configuration questions? We are not a RAMP client. 

We recently switched from an internally hosted exchange environment where PAH was sending successfully to G-suite. PAH seems to be the last hold-out not wanting to make the switch. We've updated TR_PAHT_CONFIGURATION as well as TIM with every combination of settings we can think of. We've also tried from the old server where PAH had previously been working as well as from a brand new installation on a different server. 

The PAH service finds the tickets, marks them as having been printed, and reports that they've been successfully sent. They aren't being delivered, however, and aren't even getting as far as showing up at all in the G-suite gmail logs.

Seeming like there's an entire element to this that we're somehow missing. We're open to any suggestions at this point. 

Thanks for your time,

Luke Robertson