Quote Originally Posted by SAngeli View Post
so far I made progresses learning about postfix and being able to get it to work as Smart Host.
I wish to ask few additional questions.
Questions are good.

Quote Originally Posted by SAngeli View Post
1. if I wish to have mixed delivery of main (locally on localhost and Smart Host) is this possible? If so, where would I set this up so that if I send a mail to @localhost it would be delivered locally anf if I send a mail to user_xx@gmail.com it will be delivered via Smart Host?
Setup a local domain, like "angeli.lan", then this will work automatically with just a few settings. In postfix there is a local delivery options. Any emails send there will be delivered locally. Everything else will be sent either to a relay server that you configured or directly to the remote systems based on their MX DNS records (if the ISP doesn't firewall email). You can also setup specific transport rules to specific domains (man transport explains all). For local delivery, you do not need any MX records for your domain. Inside the /etc/postfix/main.cf file are all the settings.
mydomain =
mydestination = 
local_recipient_maps =
are the main ones. I didn't check that these were all of them - only connected to my email gateway (main job is to block spam emails), not the real email server.

$ dig google.com mx
will show the MX (Mail eXchange DNS record) You can do this for any domain. That is how email systems know where to send non-local emails.

Quote Originally Posted by SAngeli View Post
2. so far I installed postfix and Postfixc Admin. In order to also manage mail locally with the use of a web interface, what do I need to install?
I don't use any web interfaces for server admin. Sorry. I think that is a security issue. Learn to do the configs manually. There are lots of how-tos and it really is easy.

Quote Originally Posted by SAngeli View Post
Hi,So far, I understood I have to install Dovecot (for POP3 and IMAP) and I would prefer Roundcube as webmail. Is this all?
Don't know. I haven't used dovecot in years and never used roundcube. I would highly recommend only using imaps, not pop3 or pop3s, unless you want to force all email to be downloaded. This is fine for an ISP, but terrible for a business. Webmail, the last time I tried, it was trivial to setup. I used squirrelmail then. Something like 4 settings was it related to the SMTP/IMAP connections. Simple.

Quote Originally Posted by SAngeli View Post
3. Is it possible to have a complete string "atp-get install" listing all packages needed, starting from scratch, for setting up a mail server with Smart Host and local mail + web?
Sure, but the postfix package requires configuration during install. I almost always setup postfix as a satellite mail server (all email gets forwarded to the main server) so I don't recall many setup details. Sorry.

Quote Originally Posted by SAngeli View Post
Also please consider including in the list spamassassing and clamAV. Beside the fact that MySQL is already installed (as part of LAMP) do I also need any additional MySQL components to install? I read it is needed to manage user accounts and e-mail forwarding or can it be avoided?
Good luck with that. The magic of APT is that dependencies are almost always automatically completed. I'm not going to check this, but something like:
$ sudo apt-get install postfix spamassassing clamAV dovecot roundcube
would seem to be reasonable starting point - you'll need to spell the names of the packages correctly, of course. I used your spellings for consistency in this post.

MySQL is not required for email. I do not use it at all. However, for an ISP with 20,000 users, I can see where have a relational DB involved could be handy. I've never run email servers for orgs with more than 300 people, so never use mysql.

Quote Originally Posted by SAngeli View Post
4. Integration between the mail server and Webmin is done automatically or is there anything needed to be done manually or install additiona packages?
Like I said before, I consider any webgui management tool to be an added security risk on already sensitive servers. I don't use them. I don't know any professional sys admins who do in any corporate environments either. Only ISPs seem to do this where email is a free service expected, but not where they make money. Why do you think more and more ISPs are outsourcing email to Yahoo and Microsoft?