The issue of possible delayed email involves a very technical issue involving the Domain Name System (DNS) that we will try to explain. If you don’t really care why it could happen then you can disregard this “book.” The thing to remember is that there is the slightest possibility that some email could be “lost” and most all email sent to you after the cut-off time, will be delayed for 12-24 hours.
Every computer and website on the Internet has a specific address, just like every house has a specific nine-digit zip code. But with computers we don’t call them zip codes, we call them IP addresses. . Humans cannot remember these addresses, so we use names. The DNS (Domain Name System) translates Internet website and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites.
So when someone types in http://www.cnn.com their PC looks at it’s assigned DNS Server, like a card catalog in the library, and your DNS Server looks up “cnn.com” and says oh, so you want “184.108.40.206”. I guess it’s also sort of like “Sarah” on The Andy Griffith Show. When Andy would pick the phone and ask to be connected with Aunt B, Sarah connected them and then was supposed to disconnect herself.
DNS implements a distributed database to store this name and address information for all public hosts on the Internet. DNS assumes IP addresses do not change (are statically assigned rather than dynamically assigned).
The DNS database resides on a hierarchy of special database servers distributed across the entire globe. When a user types in a URL or Domain Name in the internet browser, a piece of software called the DNS resolver (usually built into the network operating system) first contacts a DNS server to determine the server’s IP address. If the DNS server does not contain the needed mapping, it will in turn forward the request to a different DNS server at the next higher level in the hierarchy. After potentially several forwarding and delegation messages are sent within the DNS hierarchy, the IP address for the given host eventually arrives at the resolver, that in turn completes the request. At this point, your web browser would attempt a connection to the web site and request the “home page.”
In other words, your computer asks it’s designated DNS server to look up http://www.cnn.com, or whatever site you are trying to look at and then if it doesn’t know, it asks a “smarter” DNS server and so on up the line until eventually if none of them know it, you get that infamous screen…”Internet Explorer Cannot Display the webpage.”
Now, to what this has to do with the email. Most large companies host their own website and email. So, if 220.127.116.11 is the IP address it would be for their website and email. But, most small companies don’t host their own website. And when you don’t host your own website but you want to control your email, then you have a web hosting company host your website and you host your own mail server, or subscribe to a hosted exchange system like Tri-State Datacom. In this instance, the web hosting company must make an entry in the DNS that says, for all email, use such and such IP address. This entry is called an MX Record. This stands for Mail Exchanger, and it is critical that the MX record point to the right address to get to the right mail server. (Other entries may be needed to also go through a Spam Filter.)
For an example of this in the normal world think about when move your office. You will need to provide the USPS with your new address and they will need to setup mail forwarding. If this isn’t done right, then some of your regular mail will not make it to your new location and will likely be “Returned to Sender, Addressee Unknown” as the Elvis Presley song said.
When making a change of servers a new MX record must be made in the DNS. If the web hosting company makes an incorrect or incomplete entry then problems will occur. As mentioned previously it takes 12-24 hours for an entry to make it all around the world to all the DNS servers. During this time someone sending you email may experience a “bounce” without explanation or the email may be held until the sending server gets a response from Tri-State Datacom’s server.
The possibility of problems is greatly reduced if you move both your email and web site to TSDC. This is why we strongly encourage moving your web site to the same company that is hosting your Exchange Server. It isn’t just about a few more dollars of web hosting fees.
Thanks for wading through this lengthy book and I hope it will help you understand why it might take so long for your email to start rolling in.