Our main CGI (yes...) written in C++ (I can hear you squirm from here) was also loosely inspired by CORBA (stop that screaming) in terms of "sort-of" exposing objects via router that automatically mapped URLs to objects, and which used XML for persistence and an XML based rendering pipeline (not that different from React components, actually, except all C++ and server side).
Hit all the 90's buzz words.
Plus lots of NFS for the shared filestore that the qmail SMTP nodes and the courier/qmail-pop3d mail receipt nodes mounted.
Plus ... yeah, you can see why I thought we'd not find each others' setups -too- surprising.
So, no, not going to squirm, because I mean, yes, I know, but it all (mostly) worked and the customers weren't unusually unhappier with us than they are with any provider ;)
However, I'd hope the SOAP part made it clear I was exaggerating a little for effect :)
... also because the idea of the custom server meaning you could have the main system's qmail handle spaced retries based on SMTP status codes amused me.