#!/bin/bash
mail_dir='/var/poczta/bla/bla/bla'
cat - > /tmp/mail.stdin
mail_from=`cat /tmp/mail.stdin | grep -m 1 "^From: "`
mail_subject=`cat /tmp/mail.stdin | grep -m 1 "^Subject: "`
mail_to=`cat /tmp/mail.stdin | grep -m 1 "^To: "`
time=`date +%s`
new_file="$mail_dir/${mail_from//From: /} [$time].txt"

a=`grep -m 1 -n "^$" /tmp/mail.stdin`
let header_lenght=${a//:/}+1

date > "$new_file"
echo $mail_from >> "$new_file"
echo $mail_subject >> "$new_file"
echo $mail_to >> "$new_file"
echo "----------------------------------------------------------------------------" >> "$new_file"

tail -n +$header_lenght /tmp/mail.stdin >> "$new_file"

rm /tmp/mail.stdin