how to update users email if there is no interface in UI

Dont go to database. instead use the power shell to do same

Add-PSSnapin Microsoft.SharePoint.PowerShell
$site = Get-SPSite http://example.com
$web = $site.RootWeb
$user = $web.SiteUsers.GetByEmail("usr@example.com")
$user.Email = "user@example.com"
$user.Update()

sharepoint 2010 sesion state

1. Enter the following PowerShell command in the SharePoint 2010 Management Shell window:

Enable-SPSessionStateService –DefaultProvision

1. On each web application for which you want to use session state, edit the web.config file and set the enableSessionState property of the pages element as follows: