Unable to deliver mail with Outlook SMTP using C# -

i'm trying send email c# application. i'm using smtpclient class , outlook smtp server perform operation.

here's code :

static void main(string[] args) {     string _sender = "testfrommail@outlook.com";     string _password = "mytestpassword";      smtpclient client = new smtpclient("smtp-mail.outlook.com");      client.port = 587;     client.deliverymethod = smtpdeliverymethod.network;     client.usedefaultcredentials = false;     system.net.networkcredential credentials =         new system.net.networkcredential(_sender, _password);     client.enablessl = true;     client.credentials = credentials;      mailmessage message = new mailmessage(_sender, "testtomail.com");     message.subject = "new subj";     message.body = "new body";     client.send(message); } 

my code runs without throwing exceptions.

the problem is, email doesn't delivered recipient. when open inbox of sender's mail, says mail couldn't delivered because had triggered junk filters.

i assume has parameter not being sent smtp client class, or security settings need configure in sender's mail.

any suggestion of great help!

error 5.4.0 means there's dns / name lookup problem. in case it's because you're trying send mail 'testtomail.com'. not valid email address.