InfoPath Form: How to fetch current user email?

Current Logged in User

SharePoint On-premise: substring-after(userName(), "\")

SharePoint Online: substring-after(substring-after(userName(), "|"), "|")


From People Picker Field

SharePoint On-premise: concat(substring-after(AccountId, "\"), "@company.com")

SharePoint Online: substring-after(substring-after(AccountId, "|"), "|")