The delay is not from us, it is from your email provider. AOL, Hotmail, MSN, a few others are very famous for holding emails when they see a lot of email coming from a particular place. Not sure if you have any options to whitelist
[email protected], that may help. I use a third party SMTP server to help with delivery. We have sent 2.7m emails since Nov 25 which is when much of all this deal craziness started. There is a good chance they are the ones putting it on hold. The forum queues them up and just spits it out, this service just shoots it out from there. As I said, I would look to see if there is a way to whitelist the email, that may help them find their way to your inbox quicker. Gmail seems to get them just fine.