[SOLVED] Configuring postfix to send system mail to an external address (DynDNS)

pwatk · 05-13-2013, 02:31 PM

I use a DynDNS host to connect to various services running on my home server.

I currently have Postfix configured to only send mail locally and all system/root mail is sent to my user account via an alias.

I'd like to reconfigure Postfix so the server can also send email externally so I can send system mail to my email account.

There are lots of tutorials out there that explain how to install a complete mail server for a domain but I'm having some difficulty understanding how to do this basic task with a DynDNS host.

Can someone please point me in the right direction?

siremaxus · 05-13-2013, 03:21 PM

Hi,

The first thing you need is a domain of your own, then you can configure your DyNDNS account for that domain. After that you can follow any guide specific for your Linux version and voilá.

Good Luck

Sire Maxus

pwatk · 05-14-2013, 06:11 AM

Thanks for your reply but I don't really need my own domain (at the moment anyway) so I was trying to avoid this.

pwatk · 05-17-2013, 04:01 PM

I'm starting to think that I need to relay the mail through another server but everywhere I look gives a different solution.

I have two questions (for starters):

1) I don't understand what the difference is between a smarthost and a satellite.

2) If I was to use a Gmail account as a relay would it appear as though I was emailing myself.

pwatk · 05-22-2013, 02:26 PM

I finally managed to figure this out using various guides I found.

Here's my notes.

First, I created a new Gmail account with an appropriate name to use as my SMTP relay.

I already had Postfix installed on a Ubuntu Server but configured to deliver local mail only so I started by reconfiguring it for 'Internet with smarthost'.

Code:

dpkg-reconfigure postfix

Once complete I had to add a few extra settings to /etc/postfix/main.cf to enable TLS and SASL authentication.

Code:

postconf -e 'relayhost = smtp.gmail.com:587'
postconf -e 'smtp_use_tls = yes'
postconf -e 'smtp_sasl_auth_enable = yes'
postconf -e 'smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd'
postconf -e 'smtp_sasl_security_options = no'
postconf -e 'smtp_sasl_security_options = noanonymous'
postconf -e 'smtp_sasl_tls_security_options = noanonymous'
postconf -e 'smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt'

I then created a hashed password file with my Gmail accounts login details. You can use an application specific password here if you have two factor authentication enabled on the account.

Code:

echo 'smtp.gmail.com:587 <user>@gmail.com:<password>' > /etc/postfix/sasl_passwd
postmap hash:/etc/postfix/sasl_passwd
rm /etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd.db

From here there are various options for forwarding mail to your desired email address. I already had all root mail sent to my user account via /etc/aliases. I could have altered this but I simply created a .forward file in my home directory and that's how it's stayed.

That's it, I now have all system mail sent to my personal email account and I can enable mail functions in the web applications on the server.

Some useful links:
Day in my life: Postfix smarthost with SMTP authentication
Setup postfix using an authorized relay host (Gmail) for RHEL/CentOS | stigmatedbrain's corner
braiden.org » Blog Archive » Using gmail as a Postfix Smarthost
Configure Postfix to Use Gmail SMTP on Ubuntu

pwatk · 10-07-2014, 04:04 PM

I recently ran into some difficulty with the above setup after changing DNS settings on my server.

To cut a long story short I should have encased the relayhost (smtp.gmail.com) in square brackets to stop postfix doing an MX lookup and failing to find the server.

The following commands fix this problem:

Code:

postconf -e 'relayhost = [smtp.gmail.com]:587'
echo '[smtp.gmail.com]:587 <user>@gmail.com:<password>' > /etc/postfix/sasl_passwd

Another useful link:
Configuring postfix to relay mail to a secure host