Just to add to this excellent reply, that you can use the Date::Manip module to change the extracted date from a string to YYMMDD format in order to create a date-stamped output filename (after stripping the extra date info in brackets).

Although this module could well be considered overkill for this simple task, it can deal with a huge variety of input formats, so is ideal for a situation (like this) where the expected data is subject to change outside your control. 
#! usr/bin/perl -w
use strict;

$\ = "\n";

use Date::Manip;
&Date_Init("TZ=GMT","DateFormat=UK"); # or whatever

while (<DATA>) {
    print UnixDate($_,"%y%m%d");
}

__DATA__
Mon,  9 Aug 2004 10:28 AM
9th August 2004 10:28
10:28 9/8/2004 
Aug 9 2004 10:28
10:28 09 August 2004

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In reply to Re^2: Renaming html email dumps according to sender and date by Mr_Jon
in thread Renaming html email dumps according to sender and date by Sigmund

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