How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Hello,

I have created a component for a website to send emails to users.

This video has really helped me with that:http://www.asp.net/web-forms/videos/how-do-i/how-do-i-create-a-reusable-component-for-sending-email-to-a-distribution-list
I want the users to send emails from the website at, say, 6 registered users in a database with the email address from a database are selected.

These six must be selected from a database with multiple users in the database that contains a zip code is included.

How can I modify the code to read a list of recipients from a data source and send an email message to a few of the recipients in the DataSource Using the System.Net.Mail class UserWebControl?

Here's the code I have so far:

Public Class DistributionList

    Dim smtpClient As New System.Net.Mail.SmtpClient()
    Dim sentEmails As Integer

    Public Function SendMail(ByVal mailMessage As System.Net.Mail.MailMessage) As Integer

        AddHandler smtpClient.SendCompleted, AddressOf SmtpClient_OnCompleted
        sentEmails = 0

        Dim recipients As DataTable = GetRecipients()

        For Each recipient As DataRow In recipients.Rows

            mailMessage.To.Clear()
            mailMessage.To.Add(New System.Net.Mail.MailAddress(recipient("Email"), (recipient("DisplayName"))))
            SendMessage(mailMessage)

        Next

        Return sentEmails

    End Function

    Private Function GetRecipients() As DataTable

        Dim table As New DataTable()

        table.Columns.Add("DisplayName")
        table.Columns.Add("Email")

        Dim row As DataRow = table.NewRow()
        row("DisplayName") = "John Doe"
        row("Email") = "John@example.com"

        table.Rows.Add(row)

        Return table

    End Function

    Private Sub SendMessage(ByVal mailMessage As System.Net.Mail.MailMessage)

        Dim userState As Object = mailMessage

        Try
            smtpClient.SendAsync(mailMessage, userState)
        Catch failedRec As System.Net.Mail.SmtpFailedRecipientsException
            'Choose to resend?
            'Log failure of send here.
        Catch smtpExc As System.Net.Mail.SmtpException
            'Log failure of SMTP client here.
        Catch ex As Exception
            'Log exception here.
        End Try

    End Sub

    Public Sub SmtpClient_OnCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs)

        Dim mailMessage As System.Net.Mail.MailMessage = CType(e.UserState, System.Net.Mail.MailMessage)

        If (e.Error Is Nothing) Then
            sentEmails = sentEmails + 1
        Else
            'Write to your error log here that an email failed.
            'Possibly include information from the mailMessage.
        End If

    End Sub

End Class

Hopefully someone can help me on the way to adjust the code.

Thanks in advance.

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Hi,

If you want to read a list of recipients from a data source, assuming you database is Sql database, then you can use SqlConnection, SqlCommand, SqlDataAdapter class to return DataTable.

For example:

connStr = ConfigurationManager.ConnectionStrings["WEBDBConnectionString"].ConnectionString;

            string cmdText = string.Empty;
            DataTable datatable = new DataTable();

            using (SqlConnection sqlConn = new SqlConnection(connStr))
            {
                cmdText = "SELECT STU_NO,STU_NAME,STU_AGE FROM Student WHERE STU_NO='" + stuNo + "'";
                SqlCommand sqlComm = new SqlCommand(cmdText);
                sqlComm.Connection = sqlConn;
                SqlDataAdapter dataAadapter = new SqlDataAdapter(sqlComm);
                dataAadapter.Fill(datatable);

                return datatable;
            }

Here is a similar post related to send email to multiple recipients.
http://forums.asp.net/t/1135988.aspx

If I misunderstood your meaning, please follow up here.

Regards,
Peter

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Hi Peter,
Thank you for your response,

I've tried with your anwser to get the correct code but it does not work.
The emails must be sent with a WebUserControl.ascx page, the code Should Be at the DistributieLijst.vb.

The distributionlist.vb can not handle the code as given by: ConfigurationManager.ConnectionStrings.
The code give errors. (I am working with Microsoft Visual Web Developer 2010Express)
I think the code modified to DistributieLijst.vb Should Be.
The code below Should Be Replaced by a code, That reads the information from thedatabase, so thats the email get sent
to Various / multiple recipients in the database.

This code sends an email to the recipient i.e. John Doe.
The code I need is:
Retrieve Name and Email Address and sorted by zip code from a database.

Private Function GetRecipients() As DataTable
 
        Dim table As New DataTable()
 
        table.Columns.Add("DisplayName")
        table.Columns.Add("Email")
 
        Dim row As DataRow = table.NewRow()
        row("DisplayName") = "John Doe"
        row("Email") = "John@example.com"
 
        table.Rows.Add(row)
 
        Return table

Do you have any idea?
Thank you,

Regards,
tvw

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Hi,

Have you add references to system.Configuration and use using statement (using System.Configuration) in your project? you don't need to place the database connection string in the web.config, you can directly use database connection string in your program, something like below:

string connectionString="Data Source=(local);Initial Catalog=WEBDB;Integrated Security=True";
SqlConnection sqlConn = new SqlConnection(connectionString)

and you can use order by in your sql query statement to sort by zip code.

Hope this helps

Regards,
Peter

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

hello,
Below is a new custom VB language code, but this unfortunately does not send mail to recipients.

When debugging, the error in Email.ascx.vb:
The address parameter can not be an empty string.
Parameter name: address.
What needs to be changed?
Hoping for your help.
Regards,
TVW

DistributionList.vb

Imports System.Data.SqlClient
Public Class DistributionList

    Dim smtpClient As New System.Net.Mail.SmtpClient()
    Dim sentEmails As Integer

    Private Property GetRecipients As New DataTable

    Public Function SendMail(ByVal mailMessage As System.Net.Mail.MailMessage) As Integer

        AddHandler smtpClient.SendCompleted, AddressOf SmtpClient_OnCompleted
        sentEmails = 0

        Dim recipients As DataTable = GetRecipients()

        For Each recipient As DataRow In recipients.Rows

            mailMessage.To.Clear()
            mailMessage.To.Add(New System.Net.Mail.MailAddress(recipient("Email"), recipient("Name")))
            SendMessage(mailMessage)

        Next

        Return sentEmails

    End Function

    Private Sub MakeMessage(ByVal mailMessage As System.Net.Mail.MailMessage)
        Dim queryString As String = _
            "SELECT Email, Name FROM recipients;"

        Using connection As New SqlClient.SqlConnection(connectionString:="Data Source=|DataDirectory|\recipient.sdf")
            Dim command As New SqlClient.SqlCommand(queryString, connection)
            connection.Open()

            Dim reader As SqlClient.SqlDataReader = command.ExecuteReader()

            ' Call Read before accessing data.
            While reader.Read()

            End While

            ' Call Close when done reading.
            reader.Close()
        End Using
    End Sub

    Private Sub SendMessage(ByVal mailMessage As System.Net.Mail.MailMessage)

        Dim userState As Object = mailMessage

        Try
            smtpClient.SendAsync(mailMessage, userState)
        Catch failedRec As System.Net.Mail.SmtpFailedRecipientsException
            'Choose to resend?
            'Log failure of send here.
        Catch smtpExc As System.Net.Mail.SmtpException
            'Log failure of SMTP client here.
        Catch ex As Exception
            'Log exception here.
        End Try

    End Sub

    Public Sub SmtpClient_OnCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs)

        Dim mailMessage As System.Net.Mail.MailMessage = CType(e.UserState, System.Net.Mail.MailMessage)

        If (e.Error Is Nothing) Then
            sentEmails = sentEmails + 1
        Else
            'Write to your error log here that an email failed.
            'Possibly include information from the mailMessage.
        End If

    End Sub


End Class

Email.ascx.vb

Imports System.Net.Mail

Partial Class Email
    Inherits System.Web.UI.UserControl

    Private _recipient As String

    Private Property recipient(p1 As String) As String
        Get
            Return _recipient
        End Get
        Set(value As String)
            _recipient = value
        End Set
    End Property

    Protected Sub btnSend_Click(ByVal sender As Object, e As System.EventArgs) Handles btnSend.Click

        Dim distList As New HDI.Net.Mail.DistributionList

        'Create instance of main mail message class
        Dim mailMessage As New System.Net.Mail.MailMessage

        mailMessage.Priority = Net.Mail.MailPriority.High

        'Configure mail mesage
        'Set the From address with user input
        mailMessage.From = New System.Net.Mail.MailAddress(txtFrom.Text.Trim())
        'Get From address in web.config
        mailMessage.From = New System.Net.Mail.MailAddress(System.Configuration.ConfigurationManager.AppSettings("fromEmailAddress"))
        mailMessage.Subject = txtSubject.Text.Trim()
        mailMessage.Body = txtBody.Text.Trim()

        Dim sentMails As Integer = distList.SendMail(mailMessage)

        'Add one to many attachments
        'mailMessage.Attachments.Add(New System.Net.Mail.Attachment("c:\temp.txt")

        'Create an instance of the SmtpClient class for sending the email
        Dim smtpClient As System.Net.Mail.SmtpClient = New System.Net.Mail.SmtpClient()

        'Use a Try/Catch block to trap sending errors
        'Especially useful when looping through multiple sends
        Try
            smtpClient.Send(mailMessage)
        Catch smtpExc As System.Net.Mail.SmtpException
            'Log error information on which email failed.
        Catch ex As Exception
            'Log general errors
        End Try

    End Sub

End Class

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

At what line does it say that?

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

In: Email.ascx.vb

mailMessage.From = New System.Net.Mail.MailAddress(txtFrom.Text.Trim())

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Then I am guessing there was nothing in txtFrom. On emails the From field is mandatory.

Typically, this is taken care of using RequiredValidator. This will give the user a warning when the field is left empty, so it can be entered before actually doing anything.

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Thank you for your response,

When the From field is left blank I get the above error. And I can see in Web Developer:

mailMessage = {MailMessage Mail System.Net..} mailMessage. From = Nothing txtFrom = {system.Web. TextBox Web controls, UI..} txtFrom .text = ""

When a valid email address is entered in the From field nothing happens in Web Developer and the Email is not sent to the recipients from database. Maybe the below code is not correct.

If you have any suggestions? Thanks in advance.

'Set the From address with user input
        mailMessage.From = New System.Net.Mail.MailAddress(txtFrom.Text.Trim())
        'Get From address in web.config
        mailMessage.From = New System.Net.Mail.MailAddress(System.Configuration.ConfigurationManager.AppSettings("FromEmailAddress"))

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

The smtpClient.Send does happen?

Have you been able to send email this way before?

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Hi,

I do not understand exactly what you meant by: The smtpClient.Send does happen?

But i can send email bij using the contactform with the same smtpClient.

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Have you used the debugger to make sure the line with "smtpClient.Send" is executed?

Good to see smtpClient can do Send. That means the focus is not on the connection to the SMTP server.

The last code you posted fills the From field from a TextBox, and then overwrites it with a value from config. Do you want the value from the TextBox to be lost? And what is in the config?

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Comment out: 'mailMessage.From = New System.Net.Mail.MailAddresSystem.Configuration.ConfigurationManager.AppSettings("FromEmailAddress"))

Debugging with the smpt client executed. When not debugging nothing happens.

config:

<appSettings>
    <add key="FromEmailAddress" value="my@email.com"/>
    <add key="HostName" value="My.smtp.com"/>
    <add key="Port" value="25"/>
    <add key="mailMessageFrom" value="my@email.com"/>
    <add key="Username" value="myUsername"/>
    <add key="UserPass" value="mypassword"/>
  </appSettings>
  <!--Mail settings-->
  <system.net>
    <mailSettings>
      <smtp>
        <network host="My.smpt.com" userName="myUsername" password="mypassword" port="25"/>
      </smtp>
    </mailSettings>
  </system.net>
  <!--Mail settings-->
  <system.web>

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Odd. Usually when SMTP client can't send a message, I get an Exception.

So, when debugging the email is sent, but when not debugging it isn't?

You may want to catch exceptions from smtpClient.Send. See if you can display any Message on the Exception in a Label on your page. See if that gets you anything.

Also, you may want to display the fields of mailMessage in Labels on your page right before the smtpClient.Send.

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

Thank you for your comment's.

Sorry, Debugging with SmptClient executed I mean debugging in VS 2010. The email is not sent.

Can you give me an example of your proposal: display the fields in labels or mail message on my page right before the smtpClient.Send?

Client Dim smtp As New System.Net.Mail.SmtpClient ()

By debugging i can see this in VS: smtp client = Nothing

System.Security.Cryptography.CryptographicException was Unhandled by user code
  Message = The handle is invalid.

  Source = mscorlib
  Stack Trace:
       at System.Security.SecureString.ProtectMemory ()
       at System.Security.SecureString.InitializeSecureString (* Char value, Int32 length)
       at System.Security.SecureString .. ctor (char * value, Int32 length)
       at System.Net.UnsafeNclNativeMethods.SecureStringHelper.CreateSecureString (String string plain)
       at System.Net.Configuration.SmtpNetworkElementInternal .. ctor (Smtp Network Element element)
       at System.Net.Configuration.SmtpSectionInternal .. ctor (Smtp Section section)
       at System.Net.Configuration.SmtpSectionInternal.GetSection ()
       at System.Net.Mail.SmtpClient.get_MailConfiguration ()
       at System.Net.Mail.SmtpClient.Initialize ()
       at System.Net.Mail.SmtpClient .. ctor ()
       at HDI.Net.Mail.DistributionList .. ctor () in C: \ Users \ Tvw \ Documents \ Visual Studio 2010 \ Projects \ WebSiteVB \ HDI.Net.Mail \ DistributionList.vb: line 8
       at Email.btnSend_Click (Object sender, EventArgs e) in C: \ Users \ Tvw \ Documents \ Visual Studio 2010 \ WebSites \ WebSiteVB \ Email.ascx.vb: line 19
       at System.Web.UI.WebControls.Button.OnClick (EventArgs e)
       at System.Web.UI.WebControls.Button.RaisePostBackEvent (String event argument)
       at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent (String event argument)
       at System.Web.UI.Page.RaisePostBackEvent (IPostBackEventHandler source control, String event argument)
       at System.Web.UI.Page.RaisePostBackEvent (Name Value Collection postData)
       at System.Web.UI.Page.ProcessRequestMain (Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  Inner Exception:

 <%@ Control Language="VB" AutoEventWireup="false" CodeFile="Email.ascx.vb" Inherits="Email" %>
<div>
  <div>
    <asp:Label ID="labFrom" runat="server" Text="From:" />&nbsp;<asp:TextBox ID="txtFrom"
      runat="server" />
  </div>
  <div>
    <asp:Label ID="labSubject" runat="server" Text="Subject:" />&nbsp;<asp:TextBox ID="txtSubject"
      runat="server" />
  </div>
  <div>
    <asp:TextBox ID="txtBody" runat="server" TextMode="MultiLine" Rows="10" Columns="80" />
  </div>
  <div>
    <asp:Button ID="btnSend" runat="server" Text="Send Email" />
  </div>
</div>

Re: How can I modify the code to read a list of recipients from a data source and send an email with WebUserControl.

What I do in cases when the debugger doesn't cut it, is put Labels in my Page. Usually directly in the Page itself. Then, in the place I need to see the values from, I simply put these values on the Text properties of the Labels. That way I can see in the resulting page what the values were, and if any were not what I expected. For instance:

labFrom.Text = mailMessage.From

And now you are getting an exception? That may be the problem.

By default, VS2010 doesn't catch Exceptions in the debugger. And since UpdatePanel can eat Exceptions, they can go unnoticed.

In VS2010, go to the Debug menu, and pick Exceptions. Turn on the Common Languate Runtime Exceptions. Then debug and see if you catch anything.