how to send mail through outlook in asp.net

<div class="_kso fsm direction_ltr _55r0" data-jsid="message">I am not able to send mail through outlook , am getting error like</div> <div class="_kso fsm direction_ltr _55r0" data-jsid="message">User not authenticated</div> <div class="_kso fsm direction_ltr _55r0" data-jsid="message">even after configuring some settings</div> <div class="_kso fsm direction_ltr _55r0" data-jsid="message">can anyone  tell me outkook settings to be configured for sending mail</div> <div class="_kso fsm direction_ltr _55r0" data-jsid="message">and in our office network we have email ids like nds.neotel.co.za . i want to configure this email id for sender of the mail</div> <div class="_kso fsm direction_ltr _55r0" data-jsid="message">Now co.za  is d extension for south africa..like we have co.in in india&l ...