The only way to get emails in seconds is to forward your email accounts to your blackberry.net account. They will arrive as fast as text messages. Otherwise I believe it's a 15 minute delay to recieve messages. Just make your sent from address one of your email addresses so nobody knows your blackberry.net address. You do not need to put a reply to address, they will automatically respond to your sent from address which will be forwarding to your blackberry.net address, which will make all emails arrive in time sensative fashion.
Sent From (email@example.com) -------> to recipient.
Recipient responds to sent from address
It arrives in seconds.