[Mailman-Developers] SMTPDeliver.py still can't do MTA VERP?

a long long *long* time ago now, I made a small hack to SMTPDeliver.py to add options to the sendmail connection EHLO, to enable VERP generation in the MTA (so that the sending system didn't have to send N messages to the MTA to accomplish VERP, but rather let the MTA deal with it). For Postfix, this is as simple as adding the XVERP option.

I still don't see any facility for doing this in a generic way; has anyone addressed the problem, and if so can someone point me at the solution?..