I need to check, "Date: Wed, 27 Sep 2006 14:17:17 -0400" and I've looked
Quite ignoring the arguments people will make against this (including me) you could do something like the following. Of course remember the date header is when the mail was made in whatever timezone it was made, not in YOUR timezone. For that you would want to check the timestamp in the received header that your system adds, not in the date header.
# Catch 1700 to 0700 header A_BAD_TIME Date =~ /\d\s(?:1[789]|2\d|0[01234567]):/ score A_BAD_TIME 0.2 Loren