Friday, November 5, 2010

Why does an email sometimes take forever to arrive?

We recently had a client ask us why an email sometimes takes forever to arrive, or sometimes never arrives at all. They had sent an email down the hall to another person in their office. They visualized it going right from their computer to the person down the hall thinking it never left their office... Realistically, this isn't the way it works. Here's our response...

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There is no specific answer to this... Sometimes emails go out lightning fast and other times they may take a while. It's the nature of the internet. Realize that you could be sending an email to the person down the hall, but it doesn't actually stay in your office when you send it going direct from your computer to their computer. It actually goes out onto the internet and can practically circle the world before it comes back to you....


Here's a quick explanation of what happens:


1) You write the email and click "send".


2) Depending on your Anti-Virus/Firewall, it may be checked and held internally on your own computer or on your own internal server. If it finds something it doesn't like, it may actually never send it at all.


3) It then goes to your Internet Service Provider's servers (i.e. Cable, DSL, ... whomever you use). Their computers check the email and if it finds something it doesn't like, it may block it and not let it go out at all.


4) It then hops from server to server to server... It literally will go through about 30 to 60 servers (which is why the internet is called "the web" - it goes through a web of servers). This may actually send your email half way across the world and back again. And, every time you send an email it takes a different route (so I could send two emails within seconds of each other and they'd both go across the world in a different way). During these hops, any server it hits checks the email and then may or may not let it through for whatever reason (bad software, junk mail issues, virus issues, ...). If it hits an "old or slow server" it may even get caught or slowed down along the way... This cannot be controlled.


5) After it hops across the Internet, it makes it's way to our web server where your domain name sits and then hits the destination email box. Our server then checks it for things as well (like running through the SpamAssassin software to try to determine if it's good or not, if the sender is legitimate, ...). There are a ton of things that gets checked in an "attempt" to reduce junk mail. If it didn't, you'd actually get thousands more emails than you already do.


6) Then, when that person goes to check their email in something like Outlook, it actually does the reverse to get back to that person from the web server - the email comes back across the internet taking 30 to 60 hops from server to server to server, into your ISP server, into your computer... When it hits your computer your own Anti-Virus/Firewall software typically checks it again before it allows you to open it.


As you can see, the path of an email is a long way. It's amazing that sometimes emails do come through within seconds of them being sent. It shows how fast the whole process and all those computers actually are... But, if anywhere along the path something doesn't look right to "any server" it may hold it, block it, or not let it through for whatever reason. It is completely out of our control and this is why sometimes it takes a long time!


Hope this explanation helps!