I get corrupted messages, when using SpamAssassin with exim and procmail. Help!

Duncan Findlay notes:

I was experiencing a munging problem with spamassasin and exim -> procmail (without fetchmail). For me the problem was in exim.conf.

To fix this, in the transports section, in the procmail_pipe section,

        command = "/usr/bin/procmail -d ${local_part}"

should be changed to

        command = "/usr/bin/procmail"

also ensure that in the same section,

        user = $local_part

This fixed the problem for me. Hopefully this might help someone else.