Duplicate checking -- warning

FYI / FWIW

        I have seen an increase in the last few months of non-unique
        message-IDs being generated by such programs as Eudora even.
        
        I keep a big idfile
        
                formail -D 819200 .procmail.idfile

        but that really shouldn't matter.
        
        Anyway, before you send those dups to /dev/null, you might want to
        make sure...
        
        ALSO: sendmail failures can cause non-delivery and requeuing of
        messages, so sending dups to /dev/null might be a very bad thing
        
        I use this as part of my duplicate checking recipe:

* ! ^Message-ID:.*MAPI\.to\.RFC822

        which prevents a lot of not-really-dups from being caught.
        
        just a friendly warning
        
                TjL