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

Email Server (Linux, Unix, Mac).md

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.

Great article! Nice and easy.
Also its easy to configure multiple domains, I did step 1 and 4 for abc.com and worked like charm.
Now I receive emails directed to anyone@localhost.com and anyone@abc.com in same inbox, which I wanted.

How about using xx.lvh.me or xip.io and then you can skip editing the /etc/hosts file?

I followed these instructions and it worked like a charm

Thanks a lot

Helpful, thanks a lot saved my time.

Brilliant stuff, saved me hours of Googling. Thanks

Worked fine for a while, but for some reason this stopped working for me after rebooting. Thunderbird keeps being "Unable to locate mail spool file." even though it exists in /var/mail/user_name. This problem persists even after removing /home/user_name/.thunderbird and reinstalling both postfix and thunderbird.

Any ideas what could cause this?

EDIT: Got it fixed. Turned out my environment variable $MAIL pointed at /home/user_name/Mail instead of /var/mail/user_name. I fixed this by creating a symbolic link to /var/mail/user_name with ln -s /var/mail/user_name /home/user_name/Mail

it works!, thanks man.

@roopezero I usually get this message Unable to locate mail spool file until I send an email to my local account and receive it (this will start the local pool). It's the last step in this tutorial :)

Is "ssudo service postfix reload" correct?

Thanks, save me a lot of time ;)

I had a problem which occured because I already had thunderbird installed and some mail accounts configured there. In the localhost mail configuration part was some non-local smtp server from another mail account selected. This could be fixed with adding a custom smtp server (also in Account settings). Server is localhost, port 25 (can be found out with nmap localhost). Then select this localhost server as smtp server in your local host account.

Even with my struggle this saved a lot of time for me :)

After we set up this local mail server, how about everyone can access that mail server or not, eg.test@localhost.com.
Can we provide the access right to anyone to access or use that mail or not?

I configured local Email Server as you mentioned . But I still get "Unable to locate mail spool file" in Thunderbird . Can you please show me a way to fix it. Also couldn't we create pop3 or Imap store as incoming mail server and smtp server as outgoing mail server in Locally.

@roopezero I had the same issue...thanks for the fix 👍

I'm getting an error regarding the SMPT settings. It reads

Sending of the message failed.
The message could not be sent because connecting to Outgoing server (SMTP) localhost failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again.

Any idea how I can test what is wrong here? When I use for example PHP to send mail, I do receive it, but when I use Thunderbird to send mail, I cannot send it.

SMTP settings in Thunderbird are:

Server Name localhost
Port 587
Connection security none
Authentication method Password, transmitted insecurely
User Name My user name

---

EDIT Changing the port number to 25 fixed it. While I was typing this all of a sudden I realized :). Just leaving this message here in case anyone else runs into this problem.

Port 25 was also a really important information for me. Thanks for the guide.

Thank you so much for this really easy to follow guide. I find it rare to find such a simple guide like this for Linux systems. Great job

Hi,

thank you for this guide!

I had to run

sudo postmap /etc/postfix/virtual

to create a file called virtual.db or else the server would reject the e-mail I was trying to send. It is also very helpful to check your /var/log/mail.log if things aren't working as expected.

Great article! Many thanks!

Great tutorial! I want to use webmail client (Roundcube/ after logic webmail pro) instead of Thunderbird. Could you, if possible, help me out with this setup, please?

just use localhost.org

I made a mistake by giving custom "user" name in /etc/postfix/virtual instead of the correct Linux username and was getting an unknown user error.

to=<customusername@localhost>, orig_to=<customusername@localhost>, relay=local, delay=0.1, delays=0.07/0/0/0.03, dsn=5.1.1, status=bounced (unknown user: "customusername")

As soon as I gave correct one the problem was solved.
Thanks for the fantastic tutorial.

Before starting/restarting postfix I had to do sudo newaliases as per ArchWiki. Otherwise Thunderbird always complains about Unable to locate mail spool file.

Awesome. Worked like charm!
id -u -n
To get Unix user account name to replace

Is it also possible to catch everything for all domains?
Say I have some application connecting to localhost:25 te send e-mail and I want everything from all domains whatsoever to be delivered to this account.

Under no circumstance may any e-mail actually be deliverable to anything else.

Edit: Found out how to do that:
/etc/postfix/virtual should then contain:
/.*/

and the /etc/postfix/main.cf should instead have:
virtual_alias_maps = pcre:/etc/postfix/virtual

For this to work you should off course also do:
sudo apt-get install postfix-pcre

Now all e-mail to whatever domain you can think of will be delivered to this mailbox.

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

What if I aleady had it installed? How do I re-prompt the configuration?

This guide doesn't say how I can set up a system to get E-mail sent to an arbitrary E-mail address. I don't just want to read E-mails locally with Thunderbird. I want E-mails to be sent to e.g. a Gmail or Yahoo E-mail address.

Really clear instructions. Thank you very much!

@aaronfranke:

This guide doesn't say how I can set up a system to get E-mail sent to an arbitrary E-mail address. I don't just want to read E-mails locally with Thunderbird. I want E-mails to be sent to e.g. a Gmail or Yahoo E-mail address.

This tutorial is named "Setup a Local Only Email Server". If you don't want a local only email server, it's not for you.

Hello there, thanks for the tutorial.
I have an issue... I setup everything as needed, port is 25... outgoing server is localhost , I can send the mail without troubles, to me, but whenever I try to get the mail, it says "Unable to locate mail spool file" - no matter what I do... is there anything I can do... thanks in advance!

EDIT:
I tried doing it on a virtual machine and it worked without any troubles. Thanks a lot for the guide, also, had to use port 25 on the outgoing server. Thanks.

Thanks a lot! Finally found a useful article on this topic. :)

I have a question, How do I configure the server so that it has Internet access, or can send to other types of domains such as gmail, outlook. etc

Thank's very much for this short tuto.

Clear and simple! Thanks a lot

Clearly documented, just follow it step by step and it works.

Truly clean and easy to follow. Thanks a lot!

works flawlessly (ubuntu 19.10) Thank you! :)

Works great. I really liked the instructions, very easy to set up. I was glad I found this as, I thought it might be tricky and with these instructions it was a few minutes on each machine.

I tried it on a desktop and a server.

Server
On the server, which only has a CLI, I wound up using mail instead of T-bird, installed via sudo apt-get install mailutils
It can be tested by sending a message to yourself by using...
mail -s "test" (your user name)@localhost
It works great to get the CRON messages on the machine.
Just type mail and you get a CLI email list. mail basics are, q to quit, m to compose, enter and spacebar to move through messages. Entering question mark ?, brings up command help.

Desktop Install
One gotcha that caught me is that I already had T-bird installed and therefore it had a default SMTP server already. For me this required what I would call step 6A to add a local STMP server.
6A. In the pane above "Account Actions" scroll, using the bar to the bottom "Outgoing Server (SMTP)".
Click Add
For description I wrote Local SMTP
Server Name: localhost
Port: 25
Username : (the user name)@localhost
Authentication Method: Password, transmitted insecurely
Connection Security: None

Then I went back into the account settings for the mail set up in step 6 and set the Outgoing Server (SMTP) to the Local SMTP

Also in /etc/hosts you can put in localhost.com as a alias and it works fine, like this...
127.0.0.1 localhost localhost.com

Awesome... Thanks... Port 25 is important..;)