Sending mail using smtp is too slow in ASP.Net

Hello i have used the code below to send e-mail on my website . But nowadays i got an error.

When i try to send from visual studio the code sends the e-mail.

But on the server (live) the process is too slow , and i don't receives any e-mail. Seems that the process is losing 

 Any advice? In advance thanks

 Dim caminho As String = cryptocredentials.Crypto.Decrypt(dec.Mail)// My email from a dll 
        Dim valor As String = cryptocredentials.Crypto.Decrypt(dec.Acesso) //  My password from a dll 

        Dim server As String = "smtp here"
        Dim body As String = ("Mensagem enviada por: ")
        body += String.Format(": {0},", Txtnome.Text.Trim())
        body += String.Format("  " & "E-mail: {0},", Txtmail.Text.Trim())
        body += String.Format("  " & "Assunto: {0},", Txttel.Text.Trim())
        body += String.Format("  " & "Mensagem: {0},", Txtmessage.Text.Trim())
        body += String.Format("  " & "Arquivos para análise: {0},", Txtlink.Text.Trim())
        Dim Message As New Mail.MailMessage()
        Message.From = New MailAddress(caminho)
        Message.To.Add(caminho)
        Message.Subject = "Contato"
        Message.Body = body
        Dim client As New SmtpClient(server)
        client.Port = 587
        client.EnableSsl = False 
        client.Credentials = New System.Net.NetworkCredential(caminho, valor)

        Try
            client.Send(Message)
        Catch ex As Exception
            ClientScript.RegisterStartupScript([GetType](), "alert", (Convert.ToString("alert('") & "Não foi possível enviar o e-mail.") + "');", True)
        Finally

            ClientScript.RegisterStartupScript([GetType](), "alert", (Convert.ToString("alert('") & "E-mail enviado com sucesso. Aguarde contato.") + "');", True)
            Response.Redirect("http://www....")
        End Try