mail Asynchronously delegate callback

 

Public Sub sendMail(ByVal subject As String, ByVal message As String)

        Try

            Dim destinations As New ArrayList

             destinations.Add(123@hotmail.com)

            Dim errDesc As String

            'mail is another function to send email

            mail("mail server", "username", "password", "from", subject, message, destinations, Nothing, Nothing, errDesc)

        Catch

        End Try

    End Sub

Public Class SendMailAsyn

    Public Sub sendMailAsyn(ByVal subject As String, ByVal message As String)

        Dim dlgt As New SendMailDelegate(AddressOf sendMail)

        Dim cb As New AsyncCallback(AddressOf SendEmailResponse)

        dlgt.BeginInvoke(subject, message, cb, dlgt)

    End Sub

Public Delegate Sub SendMailDelegate(ByVal subject As String, ByVal message As String)

    'callback method

    Public Sub SendEmailResponse(ByVal ar As IAsyncResult)

        Dim dlgt As SendMailDelegate = CType(ar.AsyncState, SendMailDelegate)

        dlgt = ar.AsyncState

        dlgt.EndInvoke(ar)

    End Sub

End Class

'catch exception and send email

Dim mail As New SendMailAsyn

 mail.sendMailAsyn("Exception", ex.Message)