Send Email in asp.net using Gmail SMTP with file attachment

web.config
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[configuration]
[system.net]
[mailSettings]
[smtp from="xxxx@gmail.com"]
[network host="smtp.gmail.com" port="587" userName="xxxx@gmail.com" password="xxxx" defaultCredentials="false" /]
[/smtp]
[/mailSettings]
[/system.net]
[/configuration]


Default.aspx
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Private Sub SendMail(ByVal source As Object, ByVal e As EventArgs)
Dim FileName As String = Server.MapPath("./files/twitter_logo.png")
Dim smtp As New System.Net.Mail.SmtpClient()
Dim smail As New System.Net.Mail.MailMessage
smail.To.Add(New System.Net.Mail.MailAddress("xxxx@gmail.com"))
smail.From = New System.Net.Mail.MailAddress("xxxx@gmail.com", "Support System")
smail.Subject = "Alert by Support System"
smail.IsBodyHtml = "true"
smail.Body = "This is test mail by xxxx"
smtp.EnableSsl = True
smail.Attachments.Add(New System.Net.Mail.Attachment(FileName))
smtp.Send(smail)
Response.Write("Email Sent Successfully!")
End Sub

Additional Helpful Code
-----------------------

This is the C# code to send emails in HTML format
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MailAddress SendFrom = new MailAddress(txtFrom.Text);
MailAddress SendTo = new MailAddress(txtTo.Text);
MailMessage MyMessage = new MailMessage(SendFrom, SendTo);

MyMessage.Subject = "Subject here";
MyMessage.IsBodyHtml = true;
MyMessage.Priority = MailPriority.Normal;
MyMessage.Body = "Some Html Body here";
SmtpClient emailClient = new SmtpClient();
emailClient.UseDefaultCredentials = true;
emailClient.DeliveryMethod = SmtpDeliveryMethod.PickupDirectoryFromIis;
emailClient.Host = "localhost";
emailClient.Send(MyMessage);

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System.Web.Mail.MailMessage objMail = new System.Web.Mail.MailMessage();
objMail.BodyFormat = System.Web.Mail.MailFormat.Html;
objMail.From = "admin@fodra.org.in";
objMail.To = "";
objMail.Subject = "test";
objMail.Priority = System.Web.Mail.MailPriority.High;
string l_body;

l_body="Test";

objMail.Body = l_body;
System.Web.Mail.SmtpMail.Send(objMail);