Query string in email body in asp.net

Question

I am having problems in creating a query string in an email body. Could you please help me?

The scenario is that a user receives my email and then I need to add in this email an "unsubscribe" link which redirects the user to the page where he/she can unsubscribe. I am sending these emails to users who have signed up already.

The code I am using to send these bulk emails is the following:

-This display the data fetched from the AspnetUser table using SQLCommand,DataSet and SqlDataAdapter:

Protected Sub btnBind_Click(sender As Object, e As EventArgs)
    Try
        conn.Open()
        Dim cmd As New SqlCommand("Select Id,FirstName,LastName,Newsletter,Email from AspNetUsers Where Newsletter=1", conn)
        Dim adp As New SqlDataAdapter(cmd)
        Dim ds As New DataSet()
        adp.Fill(ds)
        grvCustomers.DataSource = ds
        grvCustomers.DataBind()
        lbltotalcount.Text = grvCustomers.Rows.Count.ToString()
    Catch ex As SqlException
        ' Display your error messages '
        FailureText.Text = "Something went wrong with your sql server database"
        ErrorMessage.Visible = True
    Finally
        conn.Close()
    End Try
    btnBind.Visible = False
End Sub

I then retreive data and put it into a gridview and then I send the bulk email:

Protected Sub btnSend_Click(sender As Object, e As EventArgs)
    Try
        lbltotalcount.Text = String.Empty
        For Each grow As GridViewRow In grvCustomers.Rows
            Dim Id As String = grow.Cells(0).Text.Trim()
            Dim FirstName As String = grow.Cells(1).Text.Trim()
            Dim LastName As String = grow.Cells(2).Text.Trim()
            Dim Newsletter As String = grow.Cells(3).Text.Trim()
            Dim Email As String = grow.Cells(4).Text.Trim()

            Dim filename As String = Server.MapPath("mytemplates/email.html")
            Dim mailbody As String = System.IO.File.ReadAllText(filename)
            mailbody = mailbody.Replace("##NAME##", FirstName)
            Dim [to] As String = Email
            Dim from As String = "[email protected]"
            Dim message As New MailMessage(from, [to])
            message.Subject = "Test"
            message.Body = mailbody
            message.BodyEncoding = Encoding.UTF8
            message.IsBodyHtml = True
            Dim client As New SmtpClient("xxxx.xxxxxx.xxx", 25)
            Dim basicCredential As New System.Net.NetworkCredential("[email protected]", "xxxxxxx")
            client.UseDefaultCredentials = True
            client.Credentials = basicCredential
            Try

                client.Send(message)
                emailrecepients.Visible = False
                emailsent.Visible = True
            Catch ex As Exception
                ' Display your error messages '
                FailureText.Text = "Emails did't go through for some reasons"
                ErrorMessage.Visible = True
            End Try
        Next
    Catch ex As SqlException
        ' Display your error messages '
        FailureText.Text = "Something went wrong with your connection to sql server database"
        ErrorMessage.Visible = True
    Finally
        conn.Close()
    End Try
End Sub

The email is sent correctly to all users who have signed up and decided to receive my emails but how can I add the query string in this email to allow users to unsubscribe without needing to login?

Thank you in advance for sharing some code with me.

Answer 1

I found out how to accomplish that:

In send newsletter:

     Dim url As String = String.Format("http://localhost:53972/Newsletter/unsubscribe?Id={1}&Email={2}", Request.Url.Authority, Id, Server.UrlEncode(Email))
            mailbody = mailbody.Replace("##UNSUBSCRIBE##", url)

and in Unsubscribe:

Protected Sub Unsubbtn_Click(sender As Object, e As EventArgs) Handles Unsubbtn.Click
    Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString)
    'Create Command object
    Dim nonqueryCommand As SqlCommand = conn.CreateCommand()
    Try
        Dim updateSql As String = "UPDATE AspNetUsers SET Newsletter=0 WHERE Id=@Id"
        Dim UpdateCmd As New SqlCommand(updateSql, conn)
        UpdateCmd.Parameters.Add("@Newsletter", SqlDbType.Bit).Value = newslettercheckbox.Checked
        UpdateCmd.Parameters.Add("@Id", SqlDbType.NVarChar, 128).Value = Request.QueryString("Id")
        conn.Open()
        UpdateCmd.ExecuteNonQuery()
    Catch ex As System.Data.SqlClient.SqlException
        ' Display your error messages '
        FailureText.Text = "Something went wrong with your sql server database"
        ErrorMessage.Visible = True
    Finally
        conn.Close()
        conn.Dispose()
    End Try
End Sub

Thanks

Answer 2

As per your question, I think you want the user that whenever he wants to unsubscribe from the message he should get that link in the email's body. You can try like this:-

  msg.Body = "<a href='http://www.yoursite.com/SignUp.aspx?nyckel=" + uniqueid + "'></a>";

or else take a reference from here and do the customising as per your want,

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