When there are several people at your company that should communicate within one JIRA Service Desk request (you want them all to see the logged tickets), two things are needed to achieve that:
Shared mailbox in your company domain
Single JIRA account
Shared mailbox may be created by your local IT administrator. It will allow selected people to receive notifications from JIRA Service Desk. It will also be a mailbox which you will be using to log in to JIRA Service Desk Portal.
JIRA account should be created using the e-mail address of you shared mailbox. Please follow the instructions described in below article: https://knowledgebase.xtrf.eu/display/XTRFHelp/Your+Account+in+JIRA+Service+Desk
Customer support service by UserEcho