Email is serious but it’s several simple technologies at work, something we take for granted when we click compose and send. Behind each email is a powerful engine called the email server which pushes the emails through the internet. Many people use them, but how does an email server work?

To drive a car we need not have the ability to tell a carburetor from a tailpipe, but when it breaks down, that little knowledge helps. Email is less likely to crash but it definitely helps to have a broad picture of how Jim’s mail reaches Jane half across the globe in a blink of an eye.

The Big Picture ““ How does an email go from Sender to Recipient?

Each email message is nothing but a text file plus the attachments. Just like all data through the internet, an email is also broken into smaller packets. When the sender clicks the send button, all the packets are uploaded to a central computer (the email server) that hosts the email service.

The email service then relays these packets through the internet to the server which holds the email service of the recipient. The mail server of the recipient looks for his email address, locates it and places the email within the inbox. The email client reassembles the packets into a complete mail. The recipient logs into his account and downloads the email.

Step by Step ““ How the Little Parts Come Together

We use an online email service like Gmail, Yahoo Mail or AOL to compose an email, add attachments and other data files. Also, we use email client software like Thunderbird, Outlook Express, Outlook or Mac OS X’s Mail.

• When we send an email, our computer connects to our email service’s mail server. A server is a centralized computer which manages a specific type of service. An email server for instance, handles emails. The email server responsible for sending emails is called the SMTP (Simple Mail Transfer Protocol) server. One SMTP server can pass on the mail to another SMTP server and relay it to the destination through several hops.
• Every email has the sender’s address (e.g. sender@sendermail.com) and the recipient’s in the To field (e.g. recipient@recipientmail.com). When an email is sent, the email client connects to the SMTP server of the sender’s email service (e.g. mailserver.sendermail.com). The client transmits the address of the sender, the address of the recipient and the content of the message.



• The SMTP server goes to work at locating the whereabouts of the recipient. Using the recipient’s mail ID (i.e. recipient@recipientmail.com) it locates the domain name – e.g.recipientmail.com.
• Note:  If the recipient’s mail ID had the same domain name as the sender, then the process would be simpler. The SMTP server would have transferred the mail to its local outgoing mail server (POP3 or IMAP).
• Each domain name represents a unique Web address, called an Internet protocol (IP) address. Think of it as postal addresses of the internet. The link between domain names to their IP addresses is stored in the Domain Name Registry. The SMTP server then contacts the server where the registry is kept (The DNS Server). The DNS server sends back the address to the SMTP server.
• The SMTP server then proceeds to hand over the email to the SMTP server of the recipient’s email service (let’s call it mailserver.recipientmail.com). This SMTP server checks and confirms that the mail addressed to recipient@recipientmail.com belongs to it and hands it over to its counterpart ““ the POP3 server (or the IMAP server).
• Post Office Protocol (POP3) servers are the servers that do the job of receiving mails. The number “˜3′ is the version number of the protocol in use. POP3 servers have mail accounts (our email IDs). Each mail account is mapped to a username-password combination. Once the message is handed over to the POP3 server, it is kept and stored in the mail account till the recipient logs in and checks the mail.
• An email client connects to the POP3 server and tells it to allow download of the email. Once downloaded to the local machine, POP3 mailboxes do not retain a copy of the email. Thus, you cannot check your emails from another PC as it has already been downloaded. To nail this difficulty, IMAP was introduced. IMAP4 (Internet Message Access Protocol version 4) simply retains a copy of the emails on the server. This allows you to access your e-mail from any location with an internet connection.

Simple notes of difference between POP3 and IMAP4

The obvious differences between the two protocols can be felt. POP3 mails are not limited by mail sizes as they get stored locally on your computer. Also because of less server storage space they are cheaper to support. But they make it difficult to export your emails if you decide to switch email programs or even operating systems.

With IMAP you can just download them again. With IMAP, sent mail and drafts are also uploaded to the server. The one apparent disadvantage of IMAP is its slower speeds because of server based functions.

POP3 is common but IMAP4 is newer and more advantageous for some of these reasons.

I hope next time you sit down to email; you just might appreciate the synergy of technology that makes it all possible. Right now, let me get back to my inbox and check what it has in store for me.

By the way, did you know that email came much, much before the internet? Probably, as early as 1965!

For people like me who had hundreds of emails in our Yahoo inboxes (and no money in our pockets) that was a sad day. Letting Yahoo take care of our emails and not having access to important emails when we wanted them was a big disappointment. I lived with the fear of losing my emails for a long time and then one day I came across this wonderful utility called YahooPOPs!

YPOPs lets you use an offline email client to download and send emails from your Yahoo account, just as it used to be. In other words, YPOPs acts as a POP3 and SMTP proxy for your Yahoo mail account.

To get started, download the YPOPs installer and install it on your Windows machine. The installer will ask you if you want YPOPs to start automatically when Windows starts. If you want that option, say yes or leave it alone. I like to leave programs out of the start up routine, so I’ll pass on this one. I’ll manually start YPOPs when I want to.

Now, comes the configuration part.

YPOPs, when started, will quietly settle down in the task bar and to configure it, you’ll just have to right click the icon and click on “configure”.

You can leave pretty much all the settings as it is except the Network settings.

The only thing in the Network settings that I had to change for YPOPs to work on my box were the POP3 and SMTP ports. For some reason, YPOPs refused to work with the default POP and SMTP ports, so I changed the POP3 port to 5110 and the SMTP port to 5125. That’s it!

To read emails offline, I use the excellent open source program called Thunderbird.

When you start Thunderbird for the first time, it’ll ask you to set up an email account to work with. Move along, enter your name and the email address that you want to work with <username@yahoo.com> and enter localhost as the POP server and localhost as the SMTP server name. Click next and finish.

When you’re finished, Thunderbird will offer to download emails from the account that you just started. If you let it download emails right now, Thunderbird will fail with an error saying it couldn’t connect to the server or something to that effect. This is normal since, by default, Thunderbird would have chosen port 110 for POP3 and port 25 for SMTP, which is not what we set in YPOPs.

To change the port settings for Thunderbird, go to Tools -> Account Settings, and under Server Settings, change the port to 5110 from the default of 110.

To change the SMTP port, on the same window, go to Outgoing Server (SMTP) and click on Edit and change the SMTP port to 5125 from the default of 25.

That’s it. Go back to the main Thunderbird window and click on Send/Receive. You should now be able to send and receive all your Yahoo email from within Thunderbird and no one will ever come to know the difference. Plus, you never have to see those ugly advertisements on the Yahoo mail website

You don’t even have to use Thunderbird to use YPOPs. You can continue using your favorite emailing client and add a second account to be used for Yahoo mail. Just make sure that you change the POP3 and SMTP ports to match the ones you set in the YPOPs configuration window.

If you have any problems setting it up, leave a question in the comments and we’ll try and help you out.