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Setup a Local Only SMTP Email Server (Linux, Unix, Mac)

Setup a Local Only SMTP Email Server (Linux, Unix, Mac)

1 - Point localhost.com to your machine

Most of programs will not accept an email using just @localhost as domain. So, edit /etc/hosts file to make the domain localhost.com point to your machine, including this content to the file:

127.0.0.1 localhost.com

2 - Install Postfix

Fedora/CentOS/RHEL: sudo yum install postfix

Ubuntu: sudo apt-get install postfix

MacOSX: Postfix is already installed by default.

3 - Configure Postfix to Local only

  • During postfix install process, the configure text dialog will display five options:

    General type of mail configuration: 
    
    No configuration
    Internet Site
    Internet with smarthost
    Satellite system
    Local only
    
  • Select "Local Only".

  • For the domain name, use the default suggested and finish the install.

4 - Configure a Catch-all Address

Enabling this, you can use any email address ending with "@localhost" or "@localhost.com".

Example: here, my unique account is rael@localhost.com. But while testing systems, I can use any address like joe@localhost.com, foo@localhost.com, etc, because all will be redirected to rael@localhost.com

  • If not exists, create file /etc/postfix/virtual: sudo nano /etc/postfix/virtual
  • Add the following 2 lines content, replacing <your-user> with your Unix user account:
@localhost <your-user>
@localhost.com <your-user>
  • Save and close the file.
  • Configure postifx to read this file:
    • Open /etc/postfix/main.cf: sudo nano /etc/postfix/main.cf
    • And check if this line is enabled, or add it if not exists: virtual_alias_maps = hash:/etc/postfix/virtual
  • Activate it: sudo postmap /etc/postfix/virtual
  • Reload postfix: sudo systemctl restart postfix
  • If you're under non systemd distro, like Ubuntu 14.04, service restart command probably is: sudo service postfix reload

5 - Install Thunderbird

Ubuntu: sudo apt-get install thunderbird

6 - Configure Thunderbird

  • Skip the welcome screen (click in the button to use existing accounts);
  • Click in the Settings button at top right (similar to Chrome settings) then click on Preferences > Account Settings
  • Under Account Actions choose "Add Other Account"
  • Select "Unix Mailspool (Movemail)"
  • Your account will be <your-user>@localhost (of course, replace <your-user> with your user account). Don't use <your-user>@(none), use <your-user>@localhost
  • Ingoing and Outgoing server will be: localhost
  • Restart (close and reopen) Thunderbird.

7 - Start your Mail Spool file

  • This step have two purposes: test your install and stop the Unable to locate mail spool file. message.
  • Using Thunderbird, send new email to <your-user>@localhost, replacing <your-user> with your user account
  • Click on "Get Mail"
  • Test catch-all: send new email to averagejoe@localhost
  • Click on "Get Mail" and you'll see the message at Inbox.
@Applebois
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Applebois commented Jul 28, 2021

Thanks,
This is really good post !

@idea-lei
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idea-lei commented Mar 15, 2022

thanks for the tutorial.
but I could not find the correct option in section 6 -> Select "Unix Mailspool (Movemail)"
it was only one option "Newsgroup account"
how could I fix this? thx in advance

-------Edit-------
for users who does not find the "unix mailspool" option sam as me:
thunderbird has removed the "unix mailspool" support since version 91. if want to follow this instruction, install a older verison instead

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