Unable to configure nginx as mail proxy

Question

I need to use nginx as a mail proxy. I am completely new to nginx and need some help with the configuration.

Here is what I did:

First I built a service that mocks the authentication services described here: http://wiki.nginx.org/NginxMailCoreModule. For example,

curl -v -H "Host:auth.server.hostname" -H "Auth-Method:plain" -H "Auth-User:user" -H "Auth-pass:123" -H "Auth-Protocol:imap" -H "Auth-Login-Attempt:1" -H "Client-IP: 192.168.1.1" http://localhost:8080/authorize

returns the following response header:

< HTTP/1.1 200 OK
< Content-Type: text/html;charset=ISO-8859-1
< Auth-Status: OK
< Auth-Server: 192.168.1.10
< Auth-Port: 110

Second I installed nginx on my mac after installing macports:

$ sudo port -d selfupdate
$ sudo port install nginx

Third I created an nginx.conf with the following:

  worker_processes  1;

  error_log  /var/log/nginx/error.log info;

  mail {
      server_name  <my mail server here>;
      auth_http    http://localhost:8080/authorize;

      pop3_auth         plain apop cram-md5;
      pop3_capabilities "LAST" "TOP" "USER" "PIPELINING" "UIDL";

      xclient off;

      server {
          listen     110;
          protocol   pop3;
          proxy      on;
          proxy_pass_error_message  on;
      }
  }

Here is what I got running nginx:

$ nginx -V nginx version: nginx/1.2.4 configure arguments: --prefix=/opt/local --with-cc-opt='-I/opt/local/include -O2' --with-ld-opt=-L/opt/local/lib --conf-path=/opt/local/etc/nginx/nginx.conf --error-log-path=/opt/local/var/log/nginx/error.log --http-log-path=/opt/local/var/log/nginx/access.log --pid-path=/opt/local/var/run/nginx/nginx.pid --lock-path=/opt/local/var/run/nginx/nginx.lock --http-client-body-temp-path=/opt/local/var/run/nginx/client_body_temp --http-proxy-temp-path=/opt/local/var/run/nginx/proxy_temp --http-fastcgi-temp-path=/opt/local/var/run/nginx/fastcgi_temp --http-uwsgi-temp-path=/opt/local/var/run/nginx/uwsgi_temp --with-ipv6

$ nginx nginx: [emerg] unknown directive "mail" in /opt/local/etc/nginx/nginx.conf:6

The only mention of that error on the web brings up a discussion in Russian...

My questions:

Why am I getting this unknow directive?
Does my config look correct at first sight or am I missing some key component for the mail proxy to work using the authentication approach described here: http://wiki.nginx.org/NginxMailCoreModule?

Goes nginx need to get involved when my SMTP server is outgoing email only ? — Scott Stensland

Lolo Lolo · Accepted Answer · 2012-10-24T14:54:17

I got the mail proxy working so I will answer my own questions for future reference:

nginx doesn't install support for mail by default

The following is needed for nginx to process the mail directive:

$ sudo port edit nginx

==> add --with-mail at the end of the config parameters

Then (re)install nginx
In the config I included, I was missing the events:

events {
worker_connections 1024;
}
An important clarification that got me stuck for a while: the authentication service (specified with auth_http) needs to return the mail server expressed as an IP address, not a host name.
Obviously for nginx to proxy on both inbound and outbound traffic, the smtp listener needs to be added. Similar approach as with the pop3 configuration. In my case, I used port 2525, so I had

server {
listen 2525;
protocol smtp;
}

Unable to configure nginx as mail proxy

1 Answers