Understanding Email Delivery, Software, and Security
Understanding Email Delivery Over the Internet
After you create and send an email message, it is sent as packets using the Internet’s TCP/IP protocol.
Routers on the internet examine the address in each packet and send the packets along the best path. When all packets are received at the destination, they are reassembled into an email message.
You can use a mailing list to send one message to a group of people through a mail reflector, which is a program that forwards email to the mailing list. Alternatively, you can subscribe to a mailing list to receive emails such as newsletters.
How Email Software Works
When you receive an email, you need a way to read, respond to, or create new mail. You accomplish this using email software, also known as mailers.
When someone sends you an email, the message isn’t delivered directly to your computer. Instead, it is sent to a mail server. Your email software logs in to the mail server and checks for new mail.
When you want to read an email message, you instruct your software to download it to your computer. Then, you can read, save, respond to, or delete it. Email software enables you to create folders for saving emails, searching, and creating an address book or group mailing list.
Email Transmission Between Networks
When you send an email, it is first broken into packets (TCP/IP).
These packets are sent to an internal router to determine if the address is within the same network or outside of it. If the recipient is inside the network, the email is delivered directly. If the recipient is outside the network, the email passes through a firewall, which acts as a shield to secure the network from intruders. The firewall tracks the data and may prevent some packets from passing through.
At the receiving network, a gateway reassembles the packets into a complete message and translates the message into the protocol used by that network. Then, the receiving network sends the message to the specified address.
How Blackberries Deliver Email
With Blackberry devices, you don’t have to manually check for emails. The device automatically polls for new messages.
It sends a poll request over a wireless network, and the request is sent over the internet to the requester’s corporation network, which is protected by a firewall. The firewall verifies if the requester is a valid employee. Valid employee requests are allowed through, while others are blocked.
Inside the corporate network, the request is routed to a Blackberry Enterprise Server. The server forwards the request to the corporation’s email server.
The corporation’s email server receives the request and sends out the email.
The email goes to the Blackberry Enterprise Server and is then sent to the Blackberry device along the same route.
Understanding White Page Directories (LDAP)
It can be difficult to find an email address knowing only a person’s name. The LDAP (Lightweight Directory Access Protocol) is a directory that allows you to look up people’s email addresses using their names. It is located on an internet server, and the company using it is responsible for keeping the information updated.
When you run an LDAP query, it sends a bind request, indicating to the server that you want to make a request. The server responds with a bind response, confirming that you can proceed.
You type the name, and the LDAP searches its database and sends you the requested information.