Most of us have been in the habit of sending and receiving email communications quickly and without much hassle. However, few of us ever wonder what goes on to make the whole thing work.
When you send an email, you typically address it to an email address say ‘username@domainname.com’. when you press the send button, your email client, which may be a software like outlook express located on your computer or an interface provided by your email service provider say gmail.com, connects to an SMTP server. SMTP stands for Simple Mail Transfer Protocol and is a standard (like the HTTP) concerned with sending emails. The SMTP server, then reads the ‘To’ information in your mail and breaks that into two parts, username and domain name.
SMTP server then connects to a DNS (domain name system) which manages a look up of domain name vs. IP address. The IP address gives the location of the server which hosts the given domain. SMTP, having acquired, the relevant IP details, breaks the messages into different packets along with adding the information of how each packet is to be handled. There are several routers located all over the Internet which have the ability to handle and direct these packets towards their destination in the most efficient path. Since, the traffic and hence bandwidth available in data lines always fluctuate, sending packets directly is not always most efficient.
Once the packets reach their destination, they are handed over to POP3 or IMAP server. POP and IMAP stand for post office protocol and Internet message access protocol and are standards for receiving email communications. These servers then sort packets according to the information attached and place the message on user's mail client to be then accessed by her.
POP is used when the message is to be delivered on the recipient’s computer and is to be accessed only locally from that system. However, IMAP has the capability to store the message on the server itself, thereby, enabling the recipient to access her emails from anywhere in the world.