* On https://mailgun.com/app/domains click on sandbox...mailgun.org domain. Here you can see all information needed to configure odoo outgoing mail feature
* Copy API Key value into odoo
* Open menu Settings/Parameters/System Parameters
* Edit mailgun.apikey parameter
* Put API Key from mailgun into Value field and save
* Open menu Settings/Parameters/System Parameters
* Edit mailgun.apikey parameter
* Put API Key from mailgun into Value field and save
* From https://mailgun.com/cp/routes create new route