C#

// To generate as random numbers as possible, this variable must only 
// be initialized once and then reused as much as possible.
Random rand = new Random();

/// <summary>
/// Generates a random number between 0 and 99995 that is always divisible by 5.
/// </summary>
/// <returns>Returns a random integer up to 5 digits long that is evenly divisible by 5.</returns>
private int GetDivBy5()
{
   // Get a random number between 0 and 99999. 
   int divBy5 = rand.Next(0, 99999);
   // Subtract the remainder of (n/5) to make n divisible by 5.
   return divBy5 - (divBy5 % 5);
}

private void button1_Click(object sender, EventArgs e)
{
   this.textBox1.Text = this.GetDivBy5().ToString("00000");

}

int random= (rand()%18000)*5 + 10000

int random= (new Random().Next()%18000)*5 + 10000

int randomDivisibleByFive = random.Next(2000, 19999) * 5;

markymark82 wrote:

Having looked into it a little bit, I know I can send up to 5 emails concurrently using my smtp server before they start being throttled, and that I should be recycling the connections rather than creating and dropping them each time.

markymark82 wrote:

I have observed that actually recycling the connections

markymark82 wrote:

The sort of volume it could have to handle is up to around 80k messages + more as the list grows.

markymark82 wrote:

they want to use it for higher volumes

markymark82 wrote:

Unfortunately, we are using authsmtp

for (int i = 0; i <= 3; i++)
            {
                FormPpal form = new FormPPal();
                form.Show();
            }
            Application.Run();

Form2 f2 = new Form2();
f2.Show();
Form3 f3 = new Form3();
f3.Show();

Form1 f1 = new Form1();
Application.Run(f1);

Application.Run(new Form1());
Form1 f3 = new Form1();
f3.Text = "BAD PROGRAMMING STYLE INCARNATE";
Application.Run(f3);

public static void Main() {
    Application.Run(new Form1());
    Application.Run(new Form2());
}

Shameel wrote:

And if you show all forms using its Show method and call Application.Run() without arguments, the app keeps running in the background even if all the forms are closed (unless, of course, you call Application.Exit())