Strange Delay in receiving email after create user registration wizard sent??

hi,
I am using the create user wizard and have extended it with more textboxes and buttons 
in template fields.
When New User Clicks the Finish button - it sends then am email saying they have registered
but the email to new user takes about 2 hours WHERE THE BCC email I added is received almost
instantly?
I dont understand the reason for delay as most sites send straight away confirmation.
Is it problem with code below?

protected void CreateUserWizard1_CreatedUser(object sender, EventArgs e) {
mail.From = new MailAddress("xxxxxxxxxxxxxxxxxx");
mail.To.Add(CreateUserWizard1.Email);  (the delay)
mail.Bcc.Add("xxxxxxxxxxxxxxxxx");   ( this is received straight away )

//send the message System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClien ...