whitespace regex

hi all -

i've noticed that a significant amount of spam i receive contain, in the 
subject line, after a spam-style subject message ("FREE MONEY"!), a whole 
string of black white spaces, often followed by a few letters or sometimes 
letters.
so i wrote a little procmail command that i hoped would put into the folder 
all mail that, in the subject line, contained over six-ish white spaces (no 
personal e-mail i receive ever contains so many), followed by a number(s). 
so i wrote the following:
:0:
* ^Subject.*([        ]+[0-9]+)
spam

this didn't work and i then tried variations such as:

:0:
* ^Subject.*([\ \ \ \ \ \ \ \ ]+[0-9]+)
spam

(very clunky, i know) but all to no avail. reading the literature i found 
online hasn't proved helpful, nor the archives to the procmail mailing 
lists i found.
does anyone have any suggestions on how to modify this code so as recognize 
the whitespace? thanks! :)
-morgan

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