Your question is not clear.
If you are looking for way to find IP and PORT in your Java plugin,
.getString(APKeys.JIRA_BASEURL) // this will give jira's base url you can extract info from this
If you are looking for way to find SITE url in Jira Cloud plugin,
@jegadeeswaran.s Jira on Cloud is hosted on Atlassian's network so you won't get a private IP ( Private IP is only valid for items that you have hosted in your private network)
On Email Handler, do share this documentation yo your Domain Team - https://confluence.atlassian.com/adminjiracloud/creating-issues-and-comments-from-email-779288896.html
it explains all the details of Jira Mail Handler.
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