system.net.mail

“Unable to read data from the transport connection: net_io_connectionclosed.” – Windows Vista Business and SMTP

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There are several things that can cause this problem, and here are some of the things that I’ve found. Questions: You mention “Exchange” — Is this an exchange server? Does the host require authentication (maybe you need to add authentication to the client)? What I would try doing first is assigning the host to the … Read more

.Net System.Mail.Message adding multiple “To” addresses

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I wasn’t able to replicate your bug: var message = new MailMessage(); message.To.Add(“user@example.com”); message.To.Add(“user2@example.com”); message.From = new MailAddress(“test@example.com”); message.Subject = “Test”; message.Body = “Test”; var client = new SmtpClient(“localhost”, 25); client.Send(message); Dumping the contents of the To: MailAddressCollection: MailAddressCollection (2 items) DisplayName User Host Address user example.com user@example.com user2 example.com user2@example.com And the resulting e-mail … Read more

Send SMTP email using System.Net.Mail via Exchange Online (Office 365)

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Fixed a few typos in the working code above: MailMessage msg = new MailMessage(); msg.To.Add(new MailAddress(“someone@somedomain.com”, “SomeOne”)); msg.From = new MailAddress(“you@yourdomain.com”, “You”); msg.Subject = “This is a Test Mail”; msg.Body = “This is a test message using Exchange OnLine”; msg.IsBodyHtml = true; SmtpClient client = new SmtpClient(); client.UseDefaultCredentials = false; client.Credentials = new System.Net.NetworkCredential(“your user … Read more

MailMessage, difference between Sender and From properties

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Excerpt from the wiki on email: Header fields: The message header should include at least the following fields: From: The e-mail address, and optionally the name of the author(s). In many e-mail clients not changeable except through changing account settings. Also note that the “From:” field does not have to be the real sender of … Read more