unknown directive "mail" with mail option enabled

[fastingsamurai]

Sorry to bother you kind folks but I can't figure out what's going on here.

I run:

brew install nginx-full --with-mail
sudo chown root:wheel /usr/local/Cellar/nginx-full/1.8.1/bin/nginx
sudo chmod u+s /usr/local/Cellar/nginx-full/1.8.1/bin/nginx

nginx -V prints:

nginx version: nginx/1.8.1
built by clang 7.0.2 (clang-700.1.81)
built with OpenSSL 1.0.2f  28 Jan 2016
TLS SNI support enabled
configure arguments: --prefix=/usr/local/Cellar/nginx-full/1.8.1 --with-http_ssl_module --with-pcre --with-ipv6 --sbin-path=/usr/local/Cellar/nginx-full/1.8.1/bin/nginx --with-cc-opt='-I/usr/local/include -I/usr/local/Cellar/pcre/8.38/include -I/usr/local/Cellar/openssl/1.0.2f/include' --with-ld-opt='-L/usr/local/lib -L/usr/local/Cellar/pcre/8.38/lib -L/usr/local/Cellar/openssl/1.0.2f/lib' --conf-path=/usr/local/etc/nginx/nginx.conf --pid-path=/usr/local/var/run/nginx.pid --lock-path=/usr/local/var/run/nginx.lock --http-client-body-temp-path=/usr/local/var/run/nginx/client_body_temp --http-proxy-temp-path=/usr/local/var/run/nginx/proxy_temp --http-fastcgi-temp-path=/usr/local/var/run/nginx/fastcgi_temp --http-uwsgi-temp-path=/usr/local/var/run/nginx/uwsgi_temp --http-scgi-temp-path=/usr/local/var/run/nginx/scgi_temp --http-log-path=/usr/local/var/log/nginx/access.log --error-log-path=/usr/local/var/log/nginx/error.log --with-mail

My /usr/local/etc/nginx/nginx.conf looks like this:

worker_processes 1;

events { 
  worker_connections 1024;
}

http {
   ...
}

mail {
  auth_http localhost/smtpserver;
  server {
    listen 127.0.0.1:25;
    protocol smtp;
    timeout 60s;
    proxy on;
  }
}

However, when I run nginx -s reload, I get:

2016/02/05 11:06:22 [notice] 73098#0: signal process started
2016/02/05 11:06:22 [emerg] 58#0: unknown directive "mail" in /usr/local/etc/nginx/nginx.conf:117

The same configuration seems to work on CentOS. I'm running El Capitan 10.11.3 with Homebrew 0.9.5 (git revision 3446; last commit 2016-02-05).