Sharing emails from Outlook to Jira and working with them in Jira is a brand new feature for Microsoft 365 and Jira Cloud.
As soon as the email (and/or the whole email conversation) is shared from Outlook, you can access and send emails from Jira, as well. The whole conversation including future replies (made in Jira or in Outlook) is shared with everyone having access to the Jira issue.