Email has become such a common part of many people's lives that we take it for granted. Have you ever wondered how email delivery works? In some ways it's really very simple.
It starts when you create an email account somewhere, with your unique username and password. Once this is done, you have an address on a host server somewhere, and you can then send email from that address or receive email there from others.
When you sign in to your account and create a new email message, you do so in an "email client." The most common are Outlook and Outlook Express, but there are also many other email clients, some of which are web-based: That is, they don't live on your computer or other personal device, but on a web server. For example, the client is web-based if you have a gmail account through Google or a Hotmail account through MSN. Smart phones also have their own email clients, or can be used with an Internet connection to access those other web-based clients. For instance, you may use your phone to connect to Google, where you have a gmail account.
Regardless of where it lives, your email client communicates with the server where your account is hosted. When you write a message to someone, the email client formats the information (who the message is to, who it's from, date, time, size of the message, subject and the text of the message itself) and sends that to the host server.
The server verifies your account, then it breaks the recipient's email address into two parts: the username and the domain name. For instance, if you are sending mail to JodiP@hotmail.com, it would be broken down to JodiP and Hotmail.com. The server then automatically requests an IP address for the server that hosts incoming mail for Hotmail.com. Once it receives the address, it then passes the message to the other server. When the message arrives at the server where the recipient has an email account, it goes through another verification process to check that the account exists. When it verifies that JodiP is the username for a valid account, your message goes into a file for the recipient. The next time the recipient logs in to their email account, the message is delivered to their email client and becomes available for them to read.
Similarly, when you receive email from others, their messages go first to the server where their email account is hosted, then are passed on to the server where your email account is hosted. That server adds the message to a file specific to you. If several messages come in when you are not logged in to email, they are added to the file in the order received. When you log in again, the file is sent from the server to your email client, where you can read the messages.
Sometimes email messages are delayed or come back ("bounce") with a message that they are undeliverable. There are several places where email can be slowed or stopped. If your email connection to the server is not working, or the server itself is down, you will not be able to deliver the message to your host server. If the recipient's server is down, the message may not be deliverable. One of the most common reasons, though, is that the recipient's address is incorrect, and their host server does not recognize it. Double check the address if you get a bounced message. In most cases, other problems will be handled automatically, since the message will go into a queue until connection issues are resolved.
Kane Miller from Winning.Email
Kane has a background in computer engineering, but now focuses on creating new and interesting web services. His passion for improving his own email deliverability rates was the driving force behind the creation of Winning.Email.