Explanation of Webmail, POP3, IMAP, and SMTP

work in progress

This is a brief explanation for the new customer on the differences between webmail, POP3 and other email protocols you might be using at ASO. The examples here assume you have example.com as your domain name.

Webmail

If you're relatively new to using email, or new to having your own domain and web hosting, you might have only had a Hotmail, Yahoo of some other free email service previously. These accounts are easily accessible and are designed to be reached anywhere in the world by only using a web browser. Similarly, you can reach your domain's email using a web browser through the use of Webmail.

To do this, you login to http://example.com/webmail∞ and enter your email address and password.

POP3 / IMAP

In the days before Webmail was widespread, there was POP3 and IMAP.

POP3 stands for Post Office Protocol (version 3)
IMAP stands for Internet Mail Access Protocol

If you use an email client program (such as Microsoft Outlook or Outlook Express, Mozilla Thunderbird or Apple Mail.app), then you'll be using POP3 or IMAP.

When you use POP3, your email client accesses the mail server and sends your username and password. Then, it checks to see if there are new messages on the server and starts downloading them to your email client. In most cases, your email client deletes the email off the server after downloading them, so you don't keep old mail from taking up unnecessary space on the server. Sometimes, your client will leave the email on the server so you can access it from another email client on another computer or view it from Webmail.

Using IMAP is a little different. You still use an email client, but instead of downloading the email from the server like POP3, the email client reads the email directly off the server and displays it in your client. You can then delete it or leave it there for the next time you are checking email.

To configure your email client for POP3 or IMAP using ASO's servers, you'll configure your email client's settings to something similar to:

SMTP

SMTP is short for Simple Mail Transfer Protocol, and is a method for sending mail from one computer to another.

You want to send an email to your friend Bob, who has an account at otherdomain.com. You already know that Bob's email address is bob@otherdomain.com, so you send your message in your email program (or using webmail) and address it to bob@otherdomain.com. Your computer connects to the SMTP server and tells it to send to bob@otherdomain.com. The SMTP server looks at the address and says, "I don't know who bob is, but I think I can get this over to otherdomain.com". The SMTP server then performs a series of steps to find out how to get the email to otherdomain.com. Once it knows, it will then connect to the other SMTP server who is responsible for all mail for otherdomain.com. When your SMTP server talks to the otherdomain.com's SMTP server, they exchange a series of messages and ultimately, the otherdomain.com says "sure, I'll take the message to bob" or it will say something like "no, there's no bob here, why you return it back to the sender".

To configure your email client for SMTP, you'll use the settings similar to these:

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