Multi-tenant / multi smtp servers

Hi all, I hope everyone is getting ready for a good weekend.

I have a questions about multi-tenant and white labeling. We have a need
for a few customers to be white labeled and I’ve been searching all over
for the best way to get this done. Just to be clear by white labeling I’m
mean that our customers do not wish to expose to their customers that we
perform the work.

Essentially

Our customer Example.com get’s support requests from their customers at
support@example.com that in turn forwards to "EXA-queue@us.ticketsvoodoo.com
"

( an RT queue; this forward had led to it’s own unique issue of auto
replies but I’m that’s another cane of worms hehe )

When we reply to the tickets here we need those replies to go through their
SMTP servers thus obfuscating us and leaving Example.com’s customers
believing they are working on these issues. I have 50 queues so I can’t
route all of postfix; not that I think anyone would have suggested that
one.

What I’m looking at now is the use of a canonical name mapping and header
checks but I figure their must be a more elegant way to get this done.

I truly appreciate this communities help. RT community has always been one
of the best. Thank you so very much for your time.