RE: [gentoo-user] Postfix configuration in server with dynamic IP

["Dave Nebinger" <dnebinger@joat.com>]

Hey, Romildo:

> I am looking for a posftix configuration for
> my computer, which receives a dynamic IP through
> adsl.

This is exactly the setup that I'm using.  I'd suggest getting an account
through dyndns.org.  You can update it using ez-ipudate when your local ip
address changes and, from external locations, will be able to verify name
lookups.  It also means that folks will be able to send you mail at
romildo@romildo.com or whatever your domain name would happen to be.
 
> Currently I am using postfix for sending mail from
> this computer, but most of the time the IP I
> receive from my ISP is blacklisted and is rejected
> on some destinations. So I want to use my ISP
> mail server for sending mail (with athentication).

There's a couple of steps that you'll need to take to get mail from your
system piped through your ISP:

1. /etc/postfix/sasl_passwd: Edit this file to include a line like:
	mail.myisp.net username:password
Obviously you'll need to use your own values.  After creating the file,
don't forget to run "postmap sasl_passwd" to create the map file for your
installation.

2. /etc/postfix/main.cf: In this file you'll need to update the section
where you find the relayhost keyword.  You'll end up setting up lines like
the following:

relayhost = mail.myisp.net
smtp_sasl_auth_enable=yes
smtp_sasl_password_maps=hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options=

After setting these values and cycling postfix you should now be relaying
all outgoing mail through your ISP, meanwhile your postfix smtp service will
still be open to receive incoming mail.

If you check the headers on this message you should see that it's
originating from my server (mail.joat.com) but is routing through verizon
(my isp) before going off to the world.

VERY IMPORTANT NOTE: Be sure that you're not running an open mail relay
(lots of info via google about how to ensure postfix is not an open mail
relay).  Once this setup is complete, if you were open, spammers could route
mail through your server which relays through your ISP.  From your ISP's
perspective you're sending the spam yourself and they could throw you
offline.

Anyways if you need some help getting postfix working under this
configuration, give me a holler, I'm happy to help.

Re: other smtp servers for this purpose, I think you're stuck with the big
3: sendmail, postfix, and qmail.  Sendmail has it's historical issues, and
IMHO qmail with it's messed-up dependencies on daemontools is not worth the
learning curve.

Stick with postfix, it's the obvious solution to your situation, it works
for me and will work for you too.



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