How to send and receive emails in mailgun (configured for a subdomain) from the root domain
<p>Mailgun recommends creating DNS (TXT, MX,..) records for a subdomain, but states sending and receiving with the root domain is possible by later configuration. I created all necessary steps for mail.example.com at my registrar and at Mailgun (adding a domain, setting up routes, etc.). 
I can now receive and send emails to the configured example@mail.example.com.</p>

<p>What do I have to change now to be able to send and receive at example@example.com?
What are the necessary changes at the registrar, in mailgun, and in my smtp settings at gmail (for sending from gmail via mailgun)?</p>

<p>Thank you very much!</p>