Host your own email domain with Exim4

 I will show how to host your own email domain (or domains) for free!

Yeah, you can have your own pam@domain.com instead of pam1985b@gmail.com, which is more professional, and for free.

But calm down. This is a complex solution based on email redirection, using a free Gmail account behind the scenes. Yeah, it's a poor man's solution, but your email address will look professional. Your customers will never know that you are using Gmail (or whatever provider) behind the scenes.

WARNING:

This tutorial doesn't show how to implement a full POP3/SMTP service. It's only an MTA server with redirection. But it's a good enough solution for small sites.

WARNING:

If you want to host your own email domain because you are afraid of NSA or something like that, I recommend to you a psychiatrist I recommend stop selling drugs, this won't be a good solution because it uses Gmail as an SMTP/POP3 server, which means they will have access to your emails. But the process to implement a full email server is pretty similar to this, only a bit more complicated (you will have to install postfix and courier too).

# Ingredients

Shell access to a server that will manage this;

Access to the domain's DNS management;

A generic email account (eg. bob2387@google.com);

# Our recipe

1. Let's implement 3 email addresses

bob@example.com: Alias to bob.example@gmail.com;

pam@example.com: Alias to pam.example@gmail.com;

info@example.com: Alias to bob.example@gmail.com + pam.example@gmail.com;

2. Create your DNS records

Create an A record named mail pointing to your server IP;

Create an MX record named example.com pointing to mail.example.com (replace example.com with your actual domain, without www)

TIP:

After that, you can test your MX record with this tool: https://mxtoolbox.com/SuperTool.aspx(opens new window)

WARNING:

On MX Toolbox, "SMTP Test" will give an error because we haven't configurated Exim4 yet. We will fix this through this tutorial.

3. Install Exim4

sudo apt-get install exim4 exim4-base exim4-config exim4-daemon-heavy

4. Re-create the configuration files

Run:

sudo dpkg-reconfigure exim4-config

On interfaces, you need to leave it empty.

On split files?, you need to answer YES!!!.

5. Edit /etc/exim4/update-exim4.conf.conf

dc_eximconfig_configtype='internet'

dc_other_hostnames='example.com;example2.com'

dc_local_interfaces=''

dc_readhost=''

dc_relay_domains=''

dc_minimaldns='false'

dc_relay_nets=''

dc_smarthost=''

CFILEMODE='644'

dc_use_split_config='false'

dc_hide_mailname=''

dc_mailname_in_oh='true'

dc_localdelivery='mail_spool'

dc_other_hostnames is optional. You can leave it blank or even incomplete, but if you want to fill it:

Replace example.com and example2.com with your actual domains.

If you have just one domain, use something like: dc_other_hostnames='example.com'

6. Remove the override configuration file, if existing

sudo rm /etc/exim4/exim4.conf

7. Re-create the auto-generated config file (/var/lib/exim4/config.autogenerated)

sudo update-exim4.conf

8. Create a folder /etc/valias

sudo mkdir /etc/valias

9. Create a configuration file for each domain in /etc/valiases

sudo nano /etc/valiases/example.com

Contents:

bob: bob.example@gmail.com

pam: pam.example@gmail.com

info: bob.example@gmail.com, pam.example@gmail.com

*: bob.example@gmail.com, pam.example@gmail.com

TIP:

Notice the * at the last line. It's a catch-all email address. It's optional and it means that any email that doesn't match the above rules will end up there. For example, test@example.com will be sent to bob and pam in this configuration.

10. Edit /etc/exim4/conf.d/main/01_exim4-config_listmacrosdefs

Set the virtual aliases directory (/etc/valiases):

#domainlist local_domains = MAIN_LOCAL_DOMAINS

domainlist local_domains = @:localhost:dsearch;/var/mail/virtual:dsearch;/etc/valiases

11. Edit /etc/exim4/conf.d/router/350_exim4-config_vdom_aliases

vdom_aliases:

      driver = redirect

      allow_defer

      allow_fail

      domains = dsearch;/etc/valiases

      data = ${expand:${lookup{$local_part}lsearch*@{/etc/valiases/$domain}}}

      retry_use_local_part

      pipe_transport   = address_pipe

      file_transport   = address_file

      no_more

12. Add your domains to /etc/hosts (OPTIONAL – just for speed sake)

127.0.1.1       example.com

127.0.1.1       example2.com

13. Re-start exim4 service

sudo /etc/init.d/exim4 restart

14. Test if it's all working

sudo exim -bt -d-resolver bob@example.com

See logs with:

tail -f /var/log/exim4/mainlog

Check with an external tool: https://mxtoolbox.com/SuperTool.aspx(opens new window)

15. TLS (optional)

If you want to enable TLS, you can use this tutorial and a CAcert.org SSL cert for free: https://github.com/Exim/exim/wiki/EximServerSslCertificate