Doing stuff according to the time?

Hi,
  I have a .procmailrc file that forwards emails to my phone (via SMS),
but I want it to restrict at what times it forwards.

E.g. I don't want messages sent to me at 4am to come through to my phone,
unless they have been marked as Urgent, or they pass other checks imposed
by me.

Is there an easy way of doing different things according to the time in
procmail?

Thanks for any help,

Steve.


-- 
Steven Clements
Final Year Mathematics and Computer Science Undergraduate