If you are setting up a web application on your own computer you sometimes need a simple mail server that just lets you view emails, for example for a password reset mail. This article lists several solutions to quickly set up a test mail server.

Using Python

The easiest way is to use Python’s built-in smtpd module. You can start a SMTP server that simply prints the received messages with this command:

$ python -m smtpd --nosetuid --class DebuggingServer

That opens a SMTP server on port 8025, and simply prints messages that look like this:

---------- MESSAGE FOLLOWS ----------
To: test@example.com
From: Sjoerd Langkemper <s.langkemper@itsec.nl>
Subject: Test message
Message-ID: <1706ee75-c447-f365-7513-06beea36488d@qbit.nl>
Date: Sun, 27 Jan 2019 14:34:19 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0)
Gecko/20100101 Thunderbird/60.4.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Content-Language: nl

Hello world
------------ END MESSAGE ------------

A more modern SMTP module is aiosmtpd, which can be run to print email messages with the following command:

$ python -m aiosmtpd -n

The modern aiosmtpd is prefered over the deprecated smtpd. The only disadvantage is that you have to install it, whereas smtpd comes bundled with Python.

Using MailSlurper

MailSlurper is a tool programmed in Go that opens a mail server and shows all mails through a web interface. The ports it uses are specified in a configuration file, config.json. It is pretty straightforward and easy to use, and it handles HTML emails better than the Python solution described above.

MailSlurper screenshot

Using application configuration

If you are using a .NET application, you can configure mail to be stored in a specific directory instead of being sent out over SMTP. Using the specifiedPickupDirectory directive you can configure the directory to store your mails in.

Similarly, for Django there is a console email backend. Putting the following in the settings.py will display emails on the console instead of sending them:

EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'

More tools

These tools set up a temporary email server on your own computer:

Cloud services

These services provide a cloud-based email server for testing purposes:


You can have your own mail server running within minutes, making it possible to test password resets and other functionality that sends email without using your actual mail server.