SmtpClient doesn’t send FQDN when HELO domain is required

I was working on a simple
mail system and each time when I tryed to send a Mail it didn’t go
through. I think thats ought, but after a bit searching on the net and
looking in the logs i found out why it didn’t go throught no valid FQDN
for HELO domain. So it seems there was a problem with the smtpclient of
.net framework 2.0 and i have fixed it. The fix is more of a workaround
to solve it, by using reflections.

You can download it here or you can view it below

Imports System.Reflection

Public Class RFCSmtpClientInherits System.Net.Mail.SmtpClient

Private Shared ReadOnly localHostName As FieldInfo = GetLocalHostNameField()

Public Sub New(ByRef host As String, ByVal port As Integer)MyBase.New(host, port)Initialize()End Sub

Public Sub New(ByRef host As String)MyBase.New(host)Initialize()End Sub

Public Sub New()MyBase.New()Initialize()End Sub

Public Sub Initialize()Dim h As String = getFQDN()If h <> "" ThenHELODomain = hEnd IfEnd Sub

Public Property HELODomain() As StringGetIf localHostName Is Nothing ThenReturn NothingElseReturn localHostName.GetValue(Me)End IfEnd GetSet(ByVal value As String)If String.IsNullOrEmpty(value) ThenThrow New ArgumentNullException("value")ElselocalHostName.SetValue(Me, value)End IfEnd SetEnd Property

Private Shared Function GetLocalHostNameField() As FieldInfoDim flags As BindingFlags = (BindingFlags.Instance Or BindingFlags.NonPublic)Return GetType(System.Net.Mail.SmtpClient).GetField("localHostName", flags)End Function

Public Function getFQDN() As StringReturn System.Net.Dns.GetHostEntry("").HostNameEnd Function

End Class