E-SERVER

Email Server:
An email server is a computer that acts as an electronic post-office, to send and receive electronic mails. An email server usually stores the following items:
· Emails for local users
· Rules about how to handle emails
· Database of user accounts

Types of Email Servers:
The following are some of the types of email servers:
· Post Office Protocol 3 (POP 3): These servers retain the emails until you check them, and delete them after you check. This is the most common type for personal email accounts.
· Internet Message Access Protocol (IMAP): These servers let you preview, delete, and organize emails without you having to download them to your computer. These servers store a copy of the email until you delete it. This is commonly used for business accounts.
· Simple Mail Transfer Protocol (SMTP): These servers send your emails to the Internet. Since these servers handle out-going emails, they work with POP3 or IMAP to receive emails.

How an Email Server Works:
The following steps detail how an email server works:
1. When you click Send, the SMTP server (which handles out-going emails) looks for the domain name in the recipient’s address. Details of domain names and their corresponding IP addresses are stored in the DNS Server.
2. The SMTP server connects to the DNS Server and fetches the recipient’s IP address.
3. The SMTP server breaks up the email into smaller packets and sends the packets to the recipient’s domain over the Internet.
4. The packets pass through several servers before connecting to the recipient’s domain name (IP address). Once in the recipient’s domain name, checks if the recipient’s address belongs to the specified domain name, and then sends the email to the recipient’s domain name.
5. The POP3 server on the recipient’s domain name delivers the email to the specified recipient and retains it until he/she checks it.
If you are sending the email within the same domain, then the SMTP server sends the email to the local POP3 or IMAP server.
MS Exchange, IBM Lotus Domino, Novell Netmail, and Zimbra are some of the popular email servers.

Relation Between a Domain Name, an Email Address, and an Email Server
The domain name identifies one or more IP addresses. Suppose my email address is writer@work.com, and suppose hyd.com is the company that hosts work.com. If mailserv1 is the email server designated to store all the emails for work.com, then when I get an email, it is stored in mailserv1.hyd.com. mailserv1.com then delivers the email to my mail box, which is writer@work.com.
Email Client
An email client downloads your emails from an email server (usually a remote system) and stores on your system. Some popular email clients are MS Outlook, Outlook Express, Thunderbird, and Eudora.