Smtpclient send message are not receiving in yahoo mail in VB.NET

Try
			Dim email3 As New MailMessage
            Dim smtpClient As New SmtpClient("mail client")

            email3.From = New MailAddress("accounts@mail.com")
            email3.To.Add("yahoo_account@yahoo.co.in")

            email3.Subject = "Mail Subject  :=> " + DateAndTime.Now.ToString()
            email3.Body = "Email body testing :=> " + DateAndTime.Now.ToString()
            email3.IsBodyHtml = True
            
            smtpClient = New SmtpClient("mail.client.com", 26)

            smtpClient.UseDefaultCredentials = False
            smtpClient.Credentials = New NetworkCredential("username", "password")
            smtpClient.EnableSsl = False
            smtpClient.Timeout = 100000
            smtpClient.Send(email3)

            MessageBox.Show("Done")



        Catch ex As Exception

            MessageBox.Show(ex.Message.ToString())

        End Try