Yahoo! defers their email to block spam!

As Webster Graphix created www.bookcrown.com we have noticed that some confirmation emails were not working on our website. when we contacted our Web Hosting company this what we learn about Yahoo! email

The reason you do not receive the email quickly at your Yahoo email address is because Yahoo tends to defer emails. This is actually why I recently changed my personal Yahoo email account to a Gmail account since I was getting tired of Yahoo doing this. Basically what Yahoo does is they defer the email the first time it is sent. This is what they do to help prevent spamming. The emails are then placed in the server's mail queue and are attempted to be sent later on. Your test email did not arrive in your Yahoo email account's inbox when it was initially sent. I actually had to go into the server's mail queue and manually send the email again. Your Yahoo email account should have now received the test email when I manually resent it from the mail queue.

Yahoo's deferment most likely has nothing to do with your site(s) in particular.

Yahoo should Invest more money and technology into their spam blocker program because a lot of people are transferring their email to Gmail which has better service.