SMTP Credentionals checking (C#)

I want to devlop a screen for entering server, Port,Username and Password for SMT开发者_如何学PythonP (Mail sending)

So i want to provide one button for "Test" Those credentionals

How can i check credentionls are correct or not

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The simplest solution is to attempt to connect to the server and try to authenticate, if you get a bad authentication response from the server the credentials are bad.