How to send email Asynchronously in ASP.Net using Background Thread

HTML Markup

<table border="0" cellpadding="0" cellspacing="0">

    <tr>

        <td style="width: 80px">

            To:

        </td>

        <td>

            <asp:TextBox ID="txtTo" runat="server"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td>

            Subject:

        </td>

        <td>

            <asp:TextBox ID="txtSubject" runat="server"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td valign = "top">

            Body:

        </td>

        <td>

            <asp:TextBox ID="txtBody" runat="server" TextMode = "MultiLine" Height = "150" Width = "200"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td>

            File Attachment:

        </td>

        <td>

            <asp:FileUpload ID="fuAttachment" runat="server" />

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td>

            Gmail Email:

        </td>

        <td>

            <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td>

            Gmail Password:

        </td>

        <td>

            <asp:TextBox ID="txtPassword" runat="server" TextMode = "Password"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            &nbsp;

        </td>

    </tr>

    <tr>

        <td>

        </td>

        <td>

            <asp:Button Text="Send" OnClick="SendAsyncEmail" runat="server" />

        </td>

    </tr>

</table>

Namespaces

You will need to import the following namespaces

C#

using System.IO;

using System.Net;

using System.Net.Mail;

using System.Threading;

VB.Net

Imports System.IO

Imports System.Net

Imports System.Net.Mail

Imports System.Threading

Sending email asynchronously in background using Thread

C#

protected void SendAsyncEmail(object sender, EventArgs e)

{

    string to = txtTo.Text;

    string from = txtEmail.Text;

    string password = txtPassword.Text;

    string subject = txtSubject.Text;

    string body = txtBody.Text;

    HttpPostedFile postedFile = fuAttachment.PostedFile;

    Thread email = new Thread(delegate()

    {

        SendEmail(to, from, password, subject, body, postedFile);

    });

 

    email.IsBackground = true;

    email.Start();

    ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Email sent.');", true);

}

 

private void SendEmail(string to, string from, string password, string subject, string body, HttpPostedFile postedFile)

{

    using (MailMessage mm = new MailMessage(from, to))

    {

        mm.Subject = subject;

        mm.Body = body;

        if (postedFile.ContentLength > 0)

        {

            string fileName = Path.GetFileName(postedFile.FileName);

            mm.Attachments.Add(new Attachment(postedFile.InputStream, fileName));

        }

        mm.IsBodyHtml = false;

        SmtpClient smtp = new SmtpClient();

        smtp.Host = "smtp.gmail.com";

        smtp.EnableSsl = true;

        NetworkCredential NetworkCred = new NetworkCredential(from, password);

        smtp.UseDefaultCredentials = true;

        smtp.Credentials = NetworkCred;

        smtp.Port = 587;

        smtp.Send(mm);

    }

}

VB.Net

Protected Sub SendAsyncEmail(sender As Object, e As EventArgs)

    Dim [to] As String = txtTo.Text

    Dim from As String = txtEmail.Text

    Dim password As String = txtPassword.Text

    Dim subject As String = txtSubject.Text

    Dim body As String = txtBody.Text

    Dim postedFile As HttpPostedFile = fuAttachment.PostedFile

    Dim email As New Thread(Sub() SendEmail([to], from, password, subject, body, postedFile))

    email.IsBackground = True

    email.Start()

    ClientScript.RegisterStartupScript([GetType](), "alert", "alert('Email sent.');", True)

End Sub

 

Private Sub SendEmail([to] As String, from As String, password As String, subject As String, body As String, postedFile As HttpPostedFile)

    Using mm As New MailMessage(from, [to])

        mm.Subject = subject

        mm.Body = body

        If postedFile.ContentLength > 0 Then

            Dim fileName As String = Path.GetFileName(postedFile.FileName)

            mm.Attachments.Add(New Attachment(postedFile.InputStream, fileName))

        End If

        mm.IsBodyHtml = False

        Dim smtp As New SmtpClient()

        smtp.Host = "smtp.gmail.com"

        smtp.EnableSsl = True

        Dim NetworkCred As New NetworkCredential(from, password)

        smtp.UseDefaultCredentials = True

        smtp.Credentials = NetworkCred

        smtp.Port = 587

        smtp.Send(mm)

    End Using

End Sub