Simple Mail Transfer Protocol (SMTP)

The Simple Mail Transfer Protocol (SMTP) is a technical standard for transmitting electronic mail (email) over a network. Like other networking protocols, SMTP allows computers and servers to exchange data regardless of their underlying hardware or software.

Email clients

An email client is a software application that allows users to access, manage, and send emails. Email clients can be standalone applications, web-based applications, or mobile applications. Each operating system (OS) installs an email client by default. The most poular of those include Microsoft Outlook, Thunderbird and Apple Mail.

While most email services can be used via email client software running on the computer desktop, mail services can also be accessible by a web client, where a user can loginto the mail server and read their mail from a web page.

Webmail

Webmail solutions enable users to log into their mail service and read/send emails from a web pages. Hotmail and Gmail are examples of webmail solutions.

The main advantage of using a webmail solution is that users can log in from any computer or device, even from Internet cafes when travelling light.

Mail servers

A mail server, also known as an email server, is a computer software that manages the flow of email messages between email clients and the Internet. Mail servers use email protocols to process incoming requests, forward messages, and deliver them to the intended recipient. They also ensure that emails are sent to the correct recipient and try to resend them if something goes wrong.

On linux servers Sendmail is the most poular SMTP software, while on Windows servers Microsoft Exchange is commonly used. But there are many different brands of mail server software. For Linux they are too many to list but for Windows the hMailServer can be more easily customised.

Mail protocols

Mail servers can send and receive emails using one or all protocols such as IMAP, POP or SMTP for different usere scenarios. For sending and receiving mail via a website the SMTP is used while IMAP is used for reading mail via webmail solutions. POP is usually used by mail clients running on the desktop.

Security

While all mail services do their best to prevent spam and malicious mail, users still need to be careful which emails they open and especially which attachments they open. Anti-virus software is only as good as its last update and much depends on known patterns which means that there really is no foolproof solution that will protect one if they persist in opening every file in front of them.

Scam mail is unavoidable and how they get your email address may be surprising. For example, maintaining a different email address for each site/service that you join may not prevent junk mail being sent to those addresses. How they get those addresses could be from hacking their mail server or even from that service's staff. In any case one needs to be able to verify that a sender is who they claim to be, for example support@example.com might actually be hacker@hell.com and with many mail clients, they have been designed to be pretty rather practical. For example Outlook Express only showed the sender's name and not their real email address. Some webmail clients make the same mistake. Thunderbird is most recommeded as a mail client for the desktop because it exposes everything that you need to know, and by clicking View Source you can easily see which route the mail took to get to your mail service. Thunderbird is also ideal for managing multiple email address.

Copy protection

If one needs to send and receive messages that are a for-your-eyes-only scenario that cannot be copied or forwarded then you will find that there is only one service that can do that. SafeGuard Mail is the only messaging service that uses DRM and copy protection for its messages and their attachments. Is is absolutely secure because messages do not leave the server. Instead users use a webmail type service to read message from a web page. The only part that ever gets touched by third party services is a notification that a message has arrived and when messages are deleted they are removed permanently without a trace left anywhere.

History

SMTP became widely used in the early 1980s. At the time, it was a complement to the Unix to Unix Copy Program (UUCP), which was better suited for handling email transfers between machines that were intermittently connected. SMTP, on the other hand, works best when both the sending and receiving machines are connected to the network all the time. Both used a store and forward mechanism and are examples of push technology. Though Usenet's newsgroups were still propagated with UUCP between servers, UUCP as a mail transport has virtually disappeared along with the bang paths it used as message routing headers.

Sendmail was released in 1983 as one of the first mail transfer agents to implement SMTP. Over time, as BSD Unix became the most popular operating system on the Internet, Sendmail became the most common MTA (mail transfer agent).

The first Microsoft Mail product was introduced in 1988 for AppleTalk Networks. It was based on InterMail, a product that Microsoft purchased and updated. An MS-DOS client was added for PCs on AppleTalk networks.

The first release of Microsoft Exchange Server was released 1996, when it was sold as an upgrade to Microsoft Mail.

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