Pausing / resuming Dropbox from the command line (Windows)
It appears that Dropbox on Windows does not offer command line options to pause and resume.
What I found effective is to actually suspend the Dropbox process. One way to do that is to use sysinternals utility pssuspend
Once that's available in the default search path, one can issue commands from the commandline like
pssuspend Dropbox
to suspend the Dropbox process and
pssuspend -r Dropbox
to resume it.
At the beginning I was worried that Dropbox would fail to synchronize files changed while Dropbox process was suspended but it seems that the file-system change notifications are queued up correctly.