Failure sending mail .net 4.0 and window server 2008 r2

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ASP.NET

Visual Studio 2010 and .NET Framework 4.0
and os 2008 r2


you are encountering the following error

System.Net.Mail.SmtpException: Failure sending mail. —> System.IndexOutOfRangeException: Index was outside the bounds of the array.
at System.Net.Base64Stream.EncodeBytes(Byte[] buffer, Int32 offset, Int32 count, Boolean dontDeferFinalBytes, Boolean shouldAppendSpaceToCRLF)
at System.Net.Base64Stream.Write(Byte[] buffer, Int32 offset, Int32 count)
at System.Net.Mime.MimePart.Send(BaseWriter writer)
at System.Net.Mime.MimeMultiPart.Send(BaseWriter writer)
at System.Net.Mail.Message.Send(BaseWriter writer, Boolean sendEnvelope)
at System.Net.Mail.SmtpClient.Send(MailMessage message)
— End of inner exception stack trace —
at System.Net.Mail.SmtpClient.Send(MailMessage message)

It is because of a bug in .net 4, which does not allow you to upload files larger than 3MB.