Hi, First I would like to specify that I have very few experience with Linux and that I've been asked to setup an SMTP server for a small company of about 50 employees. Everyone will access the smtp server from the inside of the network.

I'll start very general and if needed will go deeper in my interrogation of setuping the different elements of my server.
I'm doing this on the latest version of Debian, Linux Kernel 2.6.x

I've been recommended to use Postfix since it's not too hard to setup and do about everything we need.
I've been inspecting our old SMTP provider emails’ header and I also notice they were using it. So I know it's possible.
I've done a lot of testing, reinstalled Linux 2-3 times since a week and I can say that I understand the basic of it. However, everywhere I look at it, I see that Postfix does not seem to let me post Email in the outside world without any sort of Authentication like Cyrus for example. Like I said, our hold SMPT provider was using Postfix but we never had to authenticate our connection to it. Even more, I was able to impersonate about anyone inside or outside out network without any problems, which was useful for me to build engine to send email from NoReply@something.com for example via our different software, without having to setup the NoReply user. I even tried to joke around with a coworker and sent him an Email from BillGate@Microsoft.com.

Basically that's what I'm trying to reproduce. A Linux SMPT mail server with open policies, minimum of security which can only be access from inside our network but sending without restriction to any outside domain.

Could, anyone tries to list the different applications I would need in order to achieve this?
For example, is PostFix with Dovcote would do the trick?

Thanks for your help ?

You seem to have read a lot of incorrect things, or interpreted them incorrectly. Postfix is an SMTP server and nothing else. By default it will forward any non local email to a suitable SMTP server for that domain without any authentication at all.

Either way, your discussion doesn't really seem to relate to the functionality you're after, as you seem to want nothing more than the most basic of implementation. With most of the postfix default in place you can send it an email from any SMTP client and, network and external services like DNS willing, it'll get there. There's very little to actually do, possibly nothing - as things like the local domain and network can be assumed based on the basic server configuration details. you may still want to set the mynetworks variables and such though, in the config file which is *VERY* well commented and extremely clear.

Now you do go on to mention dovecot, but only by name, and you've not mentioned requiring any of the functionality it provides i.e. a pop3 / imap service. If you do indeed want local users to be able to pull emails form the same machine that postfix is running on then dovecot is certainly a great choice for doing that.

Thanks for your answer,
between the time I wrote my initial post and the time you answered it, I did manage to setup (again) a really basic Postfix server with about no customization at all and surprisingly, it worked way better for my needs then most of all the other attempt I made following How-tos, tutorials, and guide I found on the internet since a week.

I'm not saying that everything is working, in fact, at this moment I only manage to test a send out from localhost telnet with an existing user, to my Gmail account, successfully.
It seems however that doing so with a mail client from another computer concludes with "Relay Access denied" error message. Still working on this, if you have any tips, I would be more then happy to hear about them.

Also, I've tried sending an email from Localhost via Telnet to another user (existing on Linux) with the same domain name, and it seems to have work but I never received it with my mail client (from my pop3 account). The only thing I can see right now is the difference in my mail.log. It seems that when Postfix is sending to a local user, it used the command Procmail -a "$EXTENSION" which it did not used when sending to Gmail. Is that making any sense ?

Ok, I managed to answer some of my own questions.
Basically, I had to play a little with the param MyNetwork and MyDestination in order to let a remote client within my network to send email. This thing fixed, I'm still confuse with the fact that Sending email to local users works, but never reach my Email inbox Via my pop3 server (not handled by me). So basically, for what I can understand, Postfix, when sending to local users, drops the mail into a mailbox folder instead of sending it to the MX address attached to my local domain.
Why and how to I fix this ?

It seems this post was pretty much one way, but at least for the sake of closing the thread completely, I just wanted to say that I solved my issue by removing my domain name from the "mydestination" parameter. It told to Postfix not to handle it as a local domain I guess but anyway it fixed my last remaining issues I had.
Now that I have a nice little SMTP server working, I'll start tweaking it a little for my needs.

Any remaining suggestion? SpamAssassin for example? Anything I should take into consideration before turning the switch on with the employees?

Thanks

Hi ManuMayer,

are you able to send mail to outside world with postfix? Can you share with me your experience?

thanks

regards