rc script REQUIRE-ing a service on another host

[Jonathan McKeown]

We had a power failure last night, and this morning I found that imapproxyd 
(running on a webserver which provides webmail) had failed to start because 
it depends on imapd (running on the mailserver, a different host), and 
imapproxyd had won the startup race.

I need to prevent the race by making one service depend on another service 
running remotely. While I sketch out some horribly untidy fix, can the 
Lazyweb tell me if there is already a neat solution for this?

Jonathan