how to not process emails over 1mb (ie attachment)

Is there any way to completely ignore an email over a certain size from
being processed by procmail... Basically I have some people that get
attachments in the 5 to 10 MB range (and higher).  Whenever they come in,
they seem to put a fair bit of a load on the machine and I would rather to
have procmail just ignore the message if it's over a certain size before it
does any processing to avoid this load... Any ideas?
Jerry