Reduce three rules to one in gnus-posting-styles

[Cecil Westerhof]

In my gnus-posting-styles I had:
        (message-news-p
         (signature-file "~/.signatureNewsgroup")
         )
        ("INBOX.Info.slime"
         (signature-file "~/.signatureNewsgroup")
         )
        ("INBOX.Info.spamassassin"
         (signature-file "~/.signatureNewsgroup")
         )

For newsgroups (the first rule) and mailing lists (the other two rules)
I want to use a different signature as for my other messages. I am a fan
of DRY so I was wondering if there is a way to condense these three
rules to one. (Makes it also more simple when extra mailing list have to
be added.) And I found one:
        ((or (message-news-p)
             (string-match "INBOX.Info.slime"        gnus-newsgroup-name)
             (string-match "INBOX.Info.spamassassin" gnus-newsgroup-name))
         (signature-file "~/.signatureNewsgroup")
         )

Also a question. In slime and spamassassin I need to use 'm' instead of
'a' because they are mailing lists. Is there a way to automatically fill
in the correct to address and go to the subject field?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof