How to config SMTP Server in web.config file

<system.net>
<mailSettings>
<smtp>
<network host="0.0.0.0" port="25" userName="yourusername" password="password"/>
</smtp>
</mailSettings>
</system.net>

Where to set up session timeout in asp.net web.config?

<configuration>
<system.web>
<sessionState timeout="20"></sessionState>
</system.web>
</configuration>
The default value is 20 minutes.

Detail:
http://msdn.microsoft.com/en-us/library/system.web.sessionstate.httpsessionstate.timeout.aspx