i wrote program 1 year ago . designed form "connect " . , winform email textbox , ...etc. i use smtp send email email understand want me know. many of customers me , "i sended email product " don't receive ! after , understand anti viruses blocking smtp , install anti virus , block smtp , send email on debug mode nothing happened (the program doesnt give me error) . so , is there programmatically way understand , smtp blocked or not ?! i use ftp send suggest of customers know , not secure way me , customers . cause many person use our iis server administrator(and im not admin of server) . can u suggest me send customer suggest in secure way ?! thank u read . most of anti-virus products catch , prevent smtp service sending it, not making requests, don't think going have luck programatically determining if intercepted. the easiest option (but not fool proof) shell out windows mailto:email@emailaddress.com i switch web servic...