Using postfix aliases as a simple mailing list without sending mail to sender

emailmailing-listpostfix

Context

I have a handful of system users having each one a company email address, handled by postfix.
Every week, we send a status email to keep everyone up to date with current developments.
Until now, this was only a few people, so it was ok to write their addresses as cc.

Now that company begins to grow, I would like to setup a virtual address for which I can add new aliases in a list, so that we can, for example, mail updates@example.com to mail everybody.

I would rather not set up a mailing list system like mailman for that, because :

  • it's a bit overkilled
  • it's a minor feature. That means that, in the long run, I will probably not pay much attention to update and inspect a mailing software – and such a low priority service with a public facing interface is the perfect recipe to have a vulnerable server.

So, my first thought was to use virtual_map and add everyone in the virtual hash for this address :

# main.cf
virtual_alias_maps = hash:/etc/postfix/virtual

# virtual
updates@example.com user1@example.com, user2@example.com, # etc

It works pretty well, except for one annoying issue : if user1 send a mail to updates, he receives a copy of that mail.

I've read a post on linux gazette presenting such a method and recommanding to use alias database. I've tried to implement that, but had the exact same problem.

Maybe worth noting, users usual mail addresses are already aliases, so that everyone can use his first name in mail address while still preventing bruteforces to be too easy, so my alias table looks something like that :

john:   john.Ed2
robert: robertFoo
alicia: alicia_bar

Question

I've searched for a postfix setting that would prevent sender to receive mail, but can't find any. Does such a setting exist ?

If not, what would be the simplest way you go to implement internal mailing list ?

Best Answer

No, such a setting does not exist.

But as commented, it could be done if one were so inclined. But it will be quite a hack, with negative consequences for the future. You'll accumulate technical debt.

When it comes to simple solutions, at literally all places I worked at, the mailing lists (to be more exact; this is a distribution list) were implemented exactly the way you did; so that a sender received a copy of his own mail.

This is not bad, quite the contrary, as with modern MUA's this enables them to display a threaded view in case of a discussion (granted, this shouldn't be too frequent on distribution lists, but happens still and is of some use). And frankly, people are used to it. Some even go as far as automatically CC each mail they send (it might sound crazy to others, but some people function differently and use their inbox for all kinds of stuff..ask the GMail guys).

If someone does not like this behaviour, he or she should set up an according filter rule on his own MUA.

This is the simplest way I would implement it. For other cases, I use mailman (which is very easy to setup) or the facilities provided by the mail server software.

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