First, you have to create an account on Mailgun.
Mailgun will ask for your credit card, to subscribe to the Free plan “Concept”. It will give you access to the free 10 000 mails by month. If you don’t want to pay, we will see later how to restrict your account, to not send after 10 000 mails.
You should land on this page:
Click on 
then 
:
Enter your domain, and click on 
:
What is interesting here is point 2 and 3, with the DNS Records:
Our domain is managed by ovh:
Note: The process listed below may differ depending on the different domain name providers.
Let’s add the first TXT record:
Then the second TXT record. Here is the first MX record:
Once all is well set and propagated, you should see something like this:
At the top of that screen, there is a “Domain Information” section:
Note down the Default SMTP Login and the Default Password.
That’s it ! Now back to Siberian.
Reach your Backoffice > Settings > Communication:
Server: smtp.mailgun.org, Auth type: Login and Port: 2525.
Don’t forget to Save, then you can test with the field “E-mail test“.