I wrote an article in May 2005 on how to
send e-mail via ASP.NET v2.0. This is a quick follow-up to that
article with additional information specifically addressing the issue of
SMTP-Authentication against a remote mail server.
Many web hosts now have their servers "locked
down" and require a username and password to send e-mail from their
servers. If you have code that uses "localhost" (the SMTP service
running on the local machine) then this should not be an issue, but if you have
a situation where you need to relay e-mail off a remote mail server that is
secured, this article should help you.
The real work is done by the NetworkCredential object. According
to MSDN, this object "provides credentials for password-based
authentication schemes such as basic, digest, NTLM, and Kerberos
authentication." The benefit of making this a two-step process rather
than passing username and password to the .Credentials property of the
SmtpClient object is not clear, but that is what is required.
Here is a fully working quick code sample that you can use
to get started on your own SMTP-Auth supporting e-mail code.
'Create a new MailMessage object and specify the"From" and "To" addresses
Dim Email As New System.Net.Mail.MailMessage( _
Email.Subject = "test subject"
Email.Body = "this is a test"
Dim mailClient As New System.Net.Mail.SmtpClient()
'This object stores the authentication values
Dim basicAuthenticationInfo As _
New System.Net.NetworkCredential("username", "password")
'Put your own, or your ISPs, mail server name onthis next line
mailClient.Host = "Mail.RemoteMailServer.com"
mailClient.UseDefaultCredentials = False
mailClient.Credentials = basicAuthenticationInfo
I would like to thank Marcus McConnell of BV Software and
also Brian Linden from CastAds Inc for their tips on how to integrate the