We are moving from a private Exchange server to Office 365. Previously, the following code worked:
System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient("Old Server Name");
smtp.Send(email);
From everything I've read, I should be able to do something like the following:
SmtpClient client = new SmtpClient();
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("your user name", "your password");
client.Port = 587; // You can use Port 25 if 587 is blocked (mine is!)
client.Host = "smtp.office365.com";
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.EnableSsl = true;
client.Send(msg);
However, if I try to use port 587, I simply get a timeout. I cannot telnet to port 587 either (telnet smtp.office365.com 587). My own Outlook client is set up for https (port 443), and I can telnet to that port - but my code just returns "SMTP server returned an invalid response". Here's some sample code that I've tried:
SmtpClient smtp = new SmtpClient("smtp.office365.com");
smtp.Port = 443;
Followed by any combination of:
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential("ID", "password");
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.EnableSsl = true;
smtp.TargetName = "STARTTLS/smtp.office365.com";
Followed by smtp.Send(email);
