Many web hosting now require sender authentication when sending e-mail through a relay server.  These mail servers have their security locked down.  Sometimes, localhost is an available SMTP server option, but if a relay server is required, a little extra code is also required.

ASP.Net offers the NetworkCredential class for this purposes.  By setting the NetworkCredential property in the SMTPClient object with the appropriate credentials, authentication can be passed with the request.  For example:

Dim smtp As New Net.Mail.SmtpClient
Dim m As New Net.Mail.MailMessage
m.Subject = "the subject"
m.From = New Net.Mail.MailAddress("email@domainname.com")
m.To.Add("john@demtron.com")
Dim Auth As New System.Net.NetworkCredential("email@domainname.com", "password")
smtp.UseDefaultCredentials = False
smtp.Credentials = Auth
smtp.Host = "smtp.domainname.com"
smtp.Send(m) 

By design, when attempting to store XML data in a cookie, the .Net Framework will raise the a HttpRequestValidationException because request validation is enabled according to Microsoft.  This is a good security mechanism to help avoid script submissions via HTTP.  Rather than turning off validation, one way to eliminate problem is to use HttpUtility.UrlEncode and HttpUtility.UrlDecode to replace suspicious characters with acceptable characters.  For example, to store an XML string to a cookie, one could use the following code:

HttpContext.Current.Response.Cookies.Set(New HttpCookie("Books", HttpUtility.UrlEncode(XMLstring)))
 

Here is a snippet of code that will convert a VB.Net DataTable into a string of XML.

Dim SB As New StringBuilder
Dim SW As New IO.StringWriter(SB)
Items.WriteXml(SW, Data.XmlWriteMode.WriteSchema)

This code writes the contents and schema of the DataTable in to a StringBuilder by way of a StringWriter object.

I found some example code on the Microsoft site at http://support.microsoft.com/kb/213360 that shows how to convert a decimal number to words using VBA.  This type of code is specially useful for tranforming currency amounts into words for printing on a check.  I needed to have this code converted to VB.Net, so here it is:

'Main Function
Function SpellNumber(ByVal MyNumber As String) As String
Dim Dollars As String = ""
Dim Cents As String = ""
Dim Temp As String = ""
Dim DecimalPlace, Count As Integer
Dim Place(9) As String
Place(2) = " Thousand "
Place(3) = " Million "
Place(4) = " Billion "
Place(5) = " Trillion "
' String representation of amount.
MyNumber = Trim(Str(MyNumber))
' Position of decimal place 0 if none.
DecimalPlace = InStr(MyNumber, ".")
' Convert cents and set MyNumber to dollar amount.
If DecimalPlace > 0 Then
Cents = GetTens(Left(Mid(MyNumber, DecimalPlace + 1) & _
"00", 2))
MyNumber = Trim(Left(MyNumber, DecimalPlace - 1))
End If
Count = 1
Do While MyNumber <> ""
Temp = GetHundreds(Right(MyNumber, 3))
If Temp <> "" Then Dollars = Temp & Place(Count) & Dollars
If Len(MyNumber) > 3 Then
MyNumber = Left(MyNumber, Len(MyNumber) - 3)
Else
MyNumber = ""
End If
Count = Count + 1
Loop
Select Case Dollars
Case ""
Dollars = "No Dollars"
Case "One"
Dollars = "One Dollar"
Case Else
Dollars = Dollars & " Dollars"
End Select
Select Case Cents
Case ""
Cents = " and No Cents"
Case "One"
Cents = " and One Cent"
Case Else
Cents = " and " & Cents & " Cents"
End Select
SpellNumber = Dollars & Cents
End Function
' Converts a number from 100-999 into text 
Function GetHundreds(ByVal MyNumber As String) As String
Dim Result As String
If Val(MyNumber) = 0 Then : Return "" : Exit Function : End If
MyNumber = Right("000" & MyNumber, 3)
' Convert the hundreds place.
If Mid(MyNumber, 1, 1) <> "0" Then
Result = GetDigit(Mid(MyNumber, 1, 1)) & " Hundred "
End If
' Convert the tens and ones place.
If Mid(MyNumber, 2, 1) <> "0" Then
Result = Result & GetTens(Mid(MyNumber, 2))
Else
Result = Result & GetDigit(Mid(MyNumber, 3))
End If
GetHundreds = Result
End Function
' Converts a number from 10 to 99 into text. 
Function GetTens(ByVal TensText As String) As String
Dim Result As String
Result = ""           ' Null out the temporary function value.
If Val(Left(TensText, 1)) = 1 Then   ' If value between 10-19...
Select Case Val(TensText)
Case 10 : Result = "Ten"
Case 11 : Result = "Eleven"
Case 12 : Result = "Twelve"
Case 13 : Result = "Thirteen"
Case 14 : Result = "Fourteen"
Case 15 : Result = "Fifteen"
Case 16 : Result = "Sixteen"
Case 17 : Result = "Seventeen"
Case 18 : Result = "Eighteen"
Case 19 : Result = "Nineteen"
Case Else
End Select
Else                                 ' If value between 20-99...
Select Case Val(Left(TensText, 1))
Case 2 : Result = "Twenty "
Case 3 : Result = "Thirty "
Case 4 : Result = "Forty "
Case 5 : Result = "Fifty "
Case 6 : Result = "Sixty "
Case 7 : Result = "Seventy "
Case 8 : Result = "Eighty "
Case 9 : Result = "Ninety "
Case Else
End Select
Result = Result & GetDigit _
(Right(TensText, 1))  ' Retrieve ones place.
End If
GetTens = Result
End Function
' Converts a number from 1 to 9 into text. 
Function GetDigit(ByVal Digit As String) As String
Select Case Val(Digit)
Case 1 : GetDigit = "One"
Case 2 : GetDigit = "Two"
Case 3 : GetDigit = "Three"
Case 4 : GetDigit = "Four"
Case 5 : GetDigit = "Five"
Case 6 : GetDigit = "Six"
Case 7 : GetDigit = "Seven"
Case 8 : GetDigit = "Eight"
Case 9 : GetDigit = "Nine"
Case Else : GetDigit = ""
End Select
End Function