So you write an email to a friend, customer, long-lost relative eg., [email protected] and click Send, what happens next?
Well, the first thing that happens is your email software will log in to the mail-server it has been configured to send emails to. Once logged in and approved to send the email, the message is then sent to the mail-server. (The mail-server will generally be a local server in your office or one that is connected to the internet somewhere out in cyberspace at your Internet Service Provider).
When the mail-server receives the email, it then has to work out where to send the email (a bit like a Post Office Sorting Office does when it determines if the letter has to be sent overseas, locally, or somewhere else at the other end of the same country).
The email server uses something called DNS (Domain Name System) to lookup the address of the mail-server that handles mail for the recipient you want to send the email to (the destination-server).
(DNS is a bit like a giant telephone directory that has all the names and addresses of every computer connected to the internet listed in it).
Once the sending-mail server has discovered the destination-server address using DNS, it then attempts to make a connection to the destination-server and if successful, will then send the email to the server, so that it can deliver the email to the mailbox of the recipient ([email protected]).
So – the email has been received by the destination mail server and my message has been delivered.
Not so fast! When the destination-server receives the email it will usually check that the message is not spam (an unwanted email message) using varying methods and scoring mechanisms to establish if the email is wanted or unwanted. If it passes those checks, it will be passed on to the mailbox of the recipient. If it fails those checks, it may be deleted, rejected or quarantined (put in a holding area for someone to manually approve it). Most of the time, spam checks get it right, some of the time, it gets it wrong.
Sometimes, the destination-server that DNS provides the address for is not the server that has the recipient’s mailbox resides on, so the destination-server may have to pass the message on to yet another server before the message is finally delivered. It is not unknown for half a dozen mail-servers to receive and pass on an email message before it actually reaches the final destination-server where the recipient’s mailbox resides.
One problem of this is that at any point along the route, the email may get deleted, rejected, quarantined or stuck (if the mail-server breaks mid-way through sending an email) and the end result of this is that your message may not actually arrive at its intended destination and you may not get a message telling you of this, so you will think the email has been delivered when it might not have been (have you ever sent a letter that has never arrived? I know I have!).
So – please remember. When you press Send and your email leaves your computer, it may not actually arrive in the Inbox of the person you want to receive it.
Some email software will allow you to request a delivery receipt for one or all emails that you send, but whilst you can request this information, the destination-server may not actually fulfil your request and tell you that the message has been delivered, so the long and the short of email is that it is not a guaranteed method of communication! Just because you sent it – does not mean that it has been received!!
I will be discussing more about spam-filtering in my next article.