In this article I will explain with an example, how to send email to multiple Users (Recipients) in ASP.Net using C# and VB.Net.
 
 
 

HTML Markup

The following HTML Markup consists of:
GridView – For displaying data.
The GridView consists of two BoundField columns and two TemplateField columns.
The TemplateField columns consists of a CheckBox and Hyperlink.
Button – For sending bulk Email.
The Button has been assigned with OnClick event handler.
<asp:GridView ID="gvRecepients" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox ID="chkSelect" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="30" />
        <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
        <asp:TemplateField HeaderText="Email">
            <ItemTemplate>
                <asp:HyperLink ID="lnkEmail" runat="server" Text='<%# Eval("Email")%>' NavigateUrl='<%# Eval("Email", "mailto:{0}")%>' />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<br />
<asp:Button Text="Send Multiple Email" runat="server" OnClick="SendMultipleEmail" />
 
 

Namespaces

You will need to import the following namespaces.
C#
using System.Data;
using System.Net;
using System.Net.Mail;
using System.Configuration;
using System.Net.Configuration;
 
VB.Net
Imports System.Data
Imports System.Net
Imports System.Net.Mail
Imports System.Configuration
Imports System.Net.Configuration
 
 

Populating the GridView

Inside the Page_Load event handler, the GridView is populated with dynamic DataTable with some dummy data.
Note: For more details on how to create DataTable dynamically and bind to GridView, please refer my article Create DataTable dynamically and bind to GridView in ASP.Net.
 
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] {
                    new DataColumn("Id", typeof(int)), 
                    new DataColumn("Name", typeof(string)), 
                    new DataColumn("Email", typeof(string)) });
        dt.Rows.Add(1, "John Hammond", "john.hammond@test.com");
        dt.Rows.Add(2, "Mudassar Khan", "mudassar.khan@test.com");
        dt.Rows.Add(3, "Suzanne Mathews", "suzzane.mathews@test.com");
        dt.Rows.Add(4, "Robert Schidner", "robert.schidner@test.com");
        gvRecepients.DataSource = dt;
        gvRecepients.DataBind();
    }
}
 
VB.Net
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.AddRange(New DataColumn(2) {
                            New DataColumn("Id", GetType(Integer)), 
                            New DataColumn("Name", GetType(String)), 
                            New DataColumn("Email", GetType(String))})
        dt.Rows.Add(1, "John Hammond", "john.hammond@test.com")
        dt.Rows.Add(2, "Mudassar Khan", "mudassar.khan@test.com")
        dt.Rows.Add(3, "Suzanne Mathews", "suzzane.mathews@test.com")
        dt.Rows.Add(4, "Robert Schidner", "robert.schidner@test.com")
        gvRecepients.DataSource = dt
        gvRecepients.DataBind()
    End If
End Sub
 
 

Sending Bulk (Mass) email using C# and VB.Net

When Send Multiple Email button is clicked, the email setting is read from SmtpSection section of Web.Config file.
Then, an object of MailMessage class is created and the Subject, Body and From address are set into its respective properties.
Next, a loop is executed over the GridView Rows and the Name and Email of all the records in GridView for which the CheckBox is checked are fetched and added to the To (recipient) address.
Finally, an object of the SmtpClient class is created and the values of Host and Port are fetched from the SmtpSection of the Web.Config file and the Email is sent using Sent method and a success message is displayed in JavaScript Alert Message Box using RegisterStartupScript method.
Note: For more details on how to send email in ASP.Net, please refer my article Send email using Gmail SMTP Mail Server in ASP.Net.
 
C#
protected void SendMultipleEmail(object sender, EventArgs e)
{
    string subject = "Welcome Email";
    string body = "Hello,<br /><br />Welcome to ASPSnippets<br /><br />Thanks.";
 
    //Read SMTP section from Web.Config.
    SmtpSection smtpSection = (SmtpSection)ConfigurationManager.GetSection("system.net/mailSettings/smtp");
    using (MailMessage mm = new MailMessage())
    {
        //Setting Subject, Body andFrom.
        mm.Subject = subject;
        mm.Body = body;
        mm.IsBodyHtml = true;
        mm.From = new MailAddress(smtpSection.From);
 
        //Looping and fetching multiplerecepient's email address.
        foreach (GridViewRow row in gvRecepients.Rows)
        {
            if ((row.FindControl("chkSelect") as CheckBox).Checked)
            {
                mm.To.Add((row.FindControl("lnkEmail") as HyperLink).Text);
            }
        }
 
        //Sending email to allrecpients.
        using (SmtpClient smtp = new SmtpClient())
        {
            smtp.Host = smtpSection.Network.Host;
            smtp.EnableSsl = smtpSection.Network.EnableSsl;
            NetworkCredential networkCred = new NetworkCredential(smtpSection.Network.UserName, smtpSection.Network.Password);
            smtp.UseDefaultCredentials = smtpSection.Network.DefaultCredentials;
            smtp.Credentials = networkCred;
            smtp.Port = smtpSection.Network.Port;
            smtp.Send(mm);
            ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Email sent.');", true);
        }
    }
}
 
VB.Net
Protected Sub SendMultipleEmail(sender As Object, e As EventArgs)
    Dim subject As String = "Welcome Email"
    Dim body As String = "Hello,<br /><br />Welcome to ASPSnippets<br /><br />Thanks."
 
    'Read SMTP section from Web.Config.
    Dim smtpSection As SmtpSection = CType(ConfigurationManager.GetSection("system.net/mailSettings/smtp"), SmtpSection)
    Using mm As MailMessage = New MailMessage()
 
        'Setting Subject, Body andFrom.
        mm.Subject = subject
        mm.Body = body
        mm.IsBodyHtml = True
        mm.From = New MailAddress(smtpSection.From)
 
        'Looping and fetching multiplerecepient's email address.
        For Each row As GridViewRow In gvRecepients.Rows
            If (TryCast(row.FindControl("chkSelect"), CheckBox)).Checked Then
                mm.To.Add((TryCast(row.FindControl("lnkEmail"), HyperLink)).Text)
            End If
        Next
 
        'Sending email to allrecpients.
        Using smtp As SmtpClient = New SmtpClient()
            smtp.Host = smtpSection.Network.Host
            smtp.EnableSsl = smtpSection.Network.EnableSsl
            Dim networkCred As NetworkCredential = New NetworkCredential(smtpSection.Network.UserName, smtpSection.Network.Password)
            smtp.UseDefaultCredentials = smtpSection.Network.DefaultCredentials
            smtp.Credentials = networkCred
            smtp.Port = smtpSection.Network.Port
            smtp.Send(mm)
            ClientScript.RegisterStartupScript(Me.GetType(), "alert", "alert('Email sent.');", True)
        End Using
    End Using
End Sub
 
 

Screenshot

Send mail to multiple Users (Recipients) in ASP.Net using C# and VB.Net
 
 

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