***************************************** Why I have to use this solution?......... Sendmail is most popular mail server, I think. And unix+sendmail is very strong solution for mail server. So you may get FreeBSD (www.freebsd.org) and sendmail (you may download latest sendmail versions from www.sendmail.org or sendmail 8.12.1 from my page). It is not hard to install FreeBSD. And it is easy to install the version of sendmail with my copying system, see below. unix+sendmail can process rather stable extremely high traffic of e-mails. ***************************************** What can I use this system for?.......... Idea 1) If you are hacker or security police man, you may want to make a UNIX server that relay many many e-mail messages and give you a hidden copy, so you may analyze each e-mail message sent via your e-mail server. Idea 2) It is very easy to make a system that receive commands from people by e-mail. For example, if subject starts from words "do remove" or any other you specified, this e-mail can be moved to your Perl program. And your Perl program may do something with it (like unsubscribing e-mail sender). Interesting: e-mail can be addressed to anyone, this doesn't matter, but if this e-mail with subject "do remove" comes to your server, then it is disappeared like nobody sent it, and you receive it. Idea 3) By the way, great schema for terrorists (there are many talks about them now): terrorist sends encoded message with some keywords in subject to his wife, but make it to go via your e-mail server. So if policeman got a copy of this message, he would think that this is message to the wife of terrorist. And terrorist group would receive this message too, as soon as it comes to your mail server where installed this system (and the message can disappear or continue to go to the wife when you receive it copy, as you wish). Idea 4) It is very nice to solve debug tasks using this system. For example you opened somekind of web-shop system and would like to know exactly how looks e-mails you sent to customers. So you install my system with sendmail 8.12.1 (by running one command "perl install.pl") and get a copy of every message then. Or even better: get only a copies of specified messages from specified senders. ***************************************** What is this and how to use it?.......... 1) This all related to "sendmail" mail server that works under UNIX (tested under FreeBSD and Linux). 2) Please, create user smmsp and a new group smmsp before you run "perl install.pl". Sometimes it is necessary, sometimes not. Anyway, install.pl is clever program, so you may run it as many times as you want, until it finish with words "Congratulations! Fantasy! Successfuly installed ALL components!" There is unique program file "install.pl" that automaticly install "sendmail 8.12.1" to your UNIX server. Very likely that you may just put sendmail.8.12.1.tar.gz to the same directory where "install.pl" is and run then command "perl install.pl" (I recomend directory /home/yourloginame/sendmail/ for this). Command "perl install.pl" would install sendmail 8.12.1 mail server automaticly. This would save much of your time, because it is not easy to install sendmail by hands. 3) Also "install.pl" automaticly install somekind of pipe to program (like you send message to address gugu@yourdomain.com and this message comes to program mftotmp, because of this line in /etc/mail/aliases : mfuser: "| /bin/mftotmp" My version of program mftotmp just save e-mail copy to harddisk, but you may do something else with messages. ). In earlier versions of sendmail it was easy to make such a command pipe, because the only thing you had to do is to add it to aliases file. Now it is hard to make it, because sendmail made much more severe security checks, and you have to enter mftotmp program to few places. For example permissions of this program (mftotmp in my example) need to be correct (and different for FreeBSD and Linux). I found good configuration and "install.pl" automaticly make it. [ it is not possible to turn of these severe security checks, using way that you may find in sendmail documentation. Maybe there are some other ways to turn it off ] 4) install.pl make unique patch to sendmail, before installation. ( see mfuserpatch for details ). This patch able to make hidden copies of e-mails that sendmail receive, send or relay. It is possible to copy or move all or specified messages. "Move" - you get a copy of e-mail, but recepient doesn't. "Copy" - you get a copy of e-mail and recepient get this e-mail too, but recepient has no way to know that someone got a copy of his e-mail. "Specified" - it is possible to copy or move only specified e-mails, like if there is keyword in subject. For example you may move all messages with keyword "Remove" to you perl script that unsubscribe people from e-mails delivery system. See mfuser.conf for details. Note: I don't use any kind of filters, so the sendmail installation is compact one and easy one. This patch make very little changes exactly to sendmail source code.