W pliku : /etc/postfix/master.cf

Zmień:

spamassassin unix - n n - - pipe
user=vmail argv=/usr/bin/spamc -f -e
/usr/sbin/sendmail -oi -f ${sender} ${recipient}

Na:

spamassassin unix - n n - - pipe
user=vmail argv=/usr/bin/spamc --max-size 30000000 -f -e
/usr/sbin/sendmail -oi -f ${sender} ${recipient}

pozdrawiam ;-)