Problem with headers encoding in sent notification?

Seems like the same bug to me as this one: http://drupal.org/node/117257.
Notification (new guestbook entry) is sent with the name of my web server instead of the defined emailadress.

Could fix the Problem for the subscriptions module easily (since there's a patch available) --> http://drupal.org/files/issues/subscriptions_sendmail_patch.txt.
Could'nt find one for the guestbook though.

Hope you can help me fix the problem.
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Appreciate any help!