UUCP connections only when remote is online

I have a quick question with UUCP.  I know how to do this with NNCP,
which is a more modern take on UUCP, but I was wondering whether this
workflow is possible with UUCP, using TCP connections.

I have machine B, which is on all the time.  Machine A wants to send a
file to machine C, where machine C may not be on the network (its
powered down).  Ideally I want to send via B, in such a way that when I
get to C, I can receive the files, or issue one or two commands,
and receive all spooled files.

Lets say I ssue the command
uucp file.txt 'B!C!~' to send the file to C via B.

The problem is, once B receives the file, it tries to send it to C,
which may not be online.  It just tries and fails, as soon as it
receives it.

Can UUCP be configered to 'test' periodically when C is online, then
send then, or alternatively, can C ping B and get it to send the file?

You could on C, specifically request the file or files, but you'd have
to remember which ones, and what names, but I'm looking for a way to get
those packets flowing once C gets online.

With NNCP, A can just send the file to C via B, and call machine B.
Then C simply calls B and it will receive everything.