
Although e-mail technology was developed to deliver e-mail it was never developed to deliver e-mail instantly and there has never be any guarantee given for instant delivery.
For instant delivery or simultaneous data exchange you can use Instant Messaging applications such as Yahoo Messenger, MSN Chat, ICQ, AIM, GChat, IRC...etc.
Yes, E-mails can be delayed for various reasons, most of them though having to do with protecting servers from Spam attacks. Whenever such attack occurs, E-mail servers use a queuing system with the first in first out principle. Though it rarely makes the headlines, the fight against spammers, hackers and viruses is going on 24/7 around the Internet and around the world as a matter of fact!
For instance, spammers will try to use any online form on our web site to try to send unwanted e-mails. If the hosting system/company detects an unusual high rate of error e-mail and/or e-mail sent they may decide to block any further e-mail sent through their system as a protection. Without such a protection the hosting system mail server could get blacklisted at the international level pretty quickly. This would prevent these mail servers to send e-mail, legitimate or not.
Open, non-protected Online forms are used to still the form recipient email account. Typically yours or your compamy's. Over the past years the industry has developped and used "Captcha" filters to make sure there is human being in front of the form and not some computer program "roboting" the fields.
Captcha are ussually a series of letters or a combination of letters & numbers that you need to type into a dedicated field. They can be hard to read! But you can always generate a new one in case the suggested captcha is not readable to you.