| Valid AOL address are 10 characters or less and also has to begin with a
| letter and not a number also.
Also, as they arrive in email, spaces are stripped out, so the characters
after the first may be only alphabetics or digits.
| How can I match this so as to be able to filter out invalid AOL From:s?
Shall we take a negative approach ...
* ! ^From: *([^a-z]|.+[^0-9a-z]|............)(_dot_)*(_at_)aol\(_dot_)com$
[If the first character of the local part is not a letter, or if any
character after the first is neither a letter nor a digit, or if there
are eleven or more characters, it's illegitimate.]
... or a positive one?
# If there are no other weighted conditions on the recipe, make sure that
# mail that isn't from AOL has a non-zero positive score:
* .000001^0
# Make the net score negative if the message is from AOL:
* -1^0 ^From:(_dot_)*(_at_)aol\(_dot_)com$
# Make it positive again if the local part is legitimate:
* 1^0 ^From: *[a-z][0-9a-z]?[0-9a-z]?[0-9a-z]?[0-9a-z]?[0-9a-z]?\
[0-9a-z]?[0-9a-z]?[0-9a-z]?[0-9a-z]?(_at_)aol\(_dot_)com$
I think that this time the negative approach was easier.