[CentOS] Centos 6.2 Postfix - forward through SMTP smarthost with SMTP-AUTH

Giles Coochey giles at coochey.net
Wed Jan 11 12:36:56 EST 2012

On 11/01/2012 10:33, Benjamin Hackl wrote:
> $ cat /etc/postfix/main.cf
> myorigin=yourdomain.com
> relayhost=your.smarthost.com
> smtp_sasl_auth_enable=yes
> ## you probably want to limit how postfix authenticates
> # smtp_sasl_security_options=noanonymous
> # smtp_sasl_mechanism_filter=login
> smtp_sasl_password_maps=hash:/etc/postfix/relay_password
> ## if something doesn't work and you need detailed(!!) logs
> #debug_peer_list=your.smarthost.com
> #debug_peer_level=3
> smtp_use_tls=yes
> #inet_interfaces = loopback-only
> #local_transport = error: disabled
> unknown_local_recipient_reject_code = 450

This is very much nearly what I got to. Note though that outbound port 
25 is blocked, but my smarthost listens on the submission port as well 
if auth is used. So my relayhost line says:


On my relayhost maillog I can see the connection appears, but mails are 
bounced with:

530 5.7.0    Authentication required (in reply to MAIL FROM command)

> $ cat /etc/postfix/relay_password
> your.smarthost.com  yourusername:yourpassword
I have tried
my.smarthost.com    username:password


[my.smarthost.com]:587    username:password


my.smarthost.com:587    username:password

With various entries in main.cf to co-incide with these... (and 
remembering to run postmap each time).

> $ postmap /etc/postfix/relay_password
> $ service postfix reload
> You can check out the commented option in the man pages or
> http://www.postfix.org/postconf.5.html
> if you're interested later/have some spare time/if it doesn't work ;-)
The line I get in the logs on my smarthost is:

Jan 11 18:31:35 gate sendmail[17441]: STARTTLS=server, 
relay=188.29.xxx.xxx.threembb.co.uk [188.29.xxx.xxx], 
version=TLSv1/SSLv3, verify=NO, cipher=DHE-RSA-AES256-SHA, bits=256/256

The mail just bounces back to the sender, nothing else on the smarthost 

More information about the CentOS mailing list