[exim] Deliver single message via smarthost

I suspect the answer to this is a simple "no", given I can't find
anything via Google or the exim manpage, but, I thought it might be
worth an ask.

Occasionally, I'd like to be able to tell exim to deliver a currently
queued message to a specific host, rather than the MXs for the
destination domain. I thought one of the myriad variations on 'exim
-Mfoo' might do it, but I can't see anything appropriate.

(Currently I'm stopping exim, switching the config to use a smarthost,
delivering the specific messages with exim -M, switching the config back
then firing exim back up again; this is far from optimal, but workable)

Any suggestions?

Cheers,

James.