Incoming Mails in ActionMailer? generated depreciation warnings. It turned
out that in quoting.rb Base64.decode64 was used. Since the Base64 module in
the ruby std-lib was hidden by the Base64 module in TMail calles to decode64
where routed to the deprecheated object in the toplevel which resulted in a
warning which then resulted in cronjobs pestering me ...

using the functions from TMail's own Base64 solved the problem:

--- /opt/local/lib/ruby/gems/1.8/gems/actionmailer-0.9.1/lib/action_mailer/vendor/tmail/quoting.rb.orig	2005-05-02 19:43:05.000000000 -0700
+++ /opt/local/lib/ruby/gems/1.8/gems/actionmailer-0.9.1/lib/action_mailer/vendor/tmail/quoting.rb	2005-05-02 19:43:28.000000000 -0700
@@ -54,7 +54,7 @@
         end
    
         def unquote_base64_and_convert_to(text, from, to)
-          text ? Iconv.iconv(to, from || "ISO-8859-1", Base64.decode64(text)).first : ""
+          text ? Iconv.iconv(to, from || "ISO-8859-1", Base64.decode(text)[0]).first : ""
         end
       end
     end