The Process of Sending an Email

All of us know, how to send an email. Did anyone know the the process behind in email delivery ? You will get an idea about the email delivery by reading on below

Mail servers did a great role in the email delivery, which is the computerized equivalent of your friendly neighbourhood mailman. Every email that is sent passes through a series of mail servers along its way to its intended recipient.

Mail servers can be broken down into two main categories: outgoing mail servers and incoming mail servers. Outgoing mail servers are known as SMTP, or Simple Mail Transfer Protocol, servers. Incoming mail servers come in two main varieties. POP3, or Post Office Protocol, version 3, servers are best known for storing sent and received messages on PCs’ local hard drives. IMAP, or Internet Message Access Protocol, servers always store copies of messages on servers. Most POP3 servers can store messages on servers, too, which is a lot more convenient.

You can check the list of mail servers from the following link;

http://en.wikipedia.org/wiki/List_of_mail_servers

The Process of Sending an Email

  • After composing a message and hitting send, your email client – whether it’s Outlook Express or Gmail – connects to your domain’s SMTP server. This server can be named many things; a standard example would be smtp.example.com.

 

  •  Your email client communicates with the SMTP server, giving it your email address, the recipient’s email address, the message body and any attachments.
  • The SMTP server processes the recipient’s email address – especially its domain. If the domain name is the same as the sender’s, the message is routed directly over to the domain’s POP3 or IMAP server – no routing between servers is needed. If the domain is different, though, the SMTP server will have to communicate with the other domain’s server.
  • In order to find the recipient’s server, the sender’s SMTP server has to communicate with the DNS, or Domain Name Server. The DNS takes the recipient’s email domain name and translates it into an IP address. The sender’s SMTP server cannot route an email properly with a domain name alone; an IP address is a unique number that is assigned to every computer that is connected to the Internet. By knowing this information, an outgoing mail server can perform its work more efficiently.
  • Now that the SMTP server has the recipient’s IP address, it can connect to its SMTP server. This isn’t usually done directly, though; instead, the message is routed along a series of unrelated SMTP servers until it arrives at its destination.

 

  •  The recipient’s SMTP server scans the incoming message. If it recognizes the domain and the user name, it forwards the message along to the domain’s POP3 or IMAP server. From there, it is placed in a sendmail queue until the recipient’s email client allows it to be downloaded. At that point, the message can be read by the recipient.

Some key notes related with mail server

Bounce message, also called a Non-Delivery Report/Receipt (NDR), or simply a bounce, is an automated electronic mail message from a mail system informing the sender of another message about a delivery problem.

Blacklisting is a process of actively monitoring the Internet for reports of email traffic fro a variety of sources sending unsolicited commercial email (SPAM) and then publicly listing that known information on Internet sites for others to reference as a measure to fight SPAM. Many ISP’s and independent organizations then use these blacklist databases as a reference filter applied to their inbound mail servers to aid in preventing SPAM and to encourage internet security.

Sender Policy Framework (SPF)  is an email validation system designed to prevent email spam by detecting email spoofing, a common vulnerability, by verifying sender IP addresses. SPF allows administrators to specify which hosts are allowed to send mail from a given domain by creating a specific SPF record (or TXT record) in the Domain Name System (DNS).

DomainKeys (DKIM) is an email authentication technology developed by Yahoo, and is primarily used as an additional anti-spam and anti-phishing method.