My answer assumes you are using JIRA Service Desk (Cloud Hosted)
First of all you will need to configure JIRA Cloud to send emails from your domain:
This will affect all projects that use the same notification scheme.
Hi Jira Service Desk community, Atlassian is on a mission to unleash the potential of all teams, and we know that tools are just one piece of that puzzle. With Jira Service Desk, we have productiv...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events