Email spamEmail spam, also referred to as junk email, spam mail, or simply spam, is unsolicited messages sent in bulk by email (spamming). The name comes from a Monty Python sketch in which the name of the canned pork product Spam is ubiquitous, unavoidable, and repetitive. Email spam has steadily grown since the early 1990s, and by 2014 was estimated to account for around 90% of total email traffic. Since the expense of the spam is borne mostly by the recipient, it is effectively postage due advertising.
Email filteringEmail filtering is the processing of email to organize it according to specified criteria. The term can apply to the intervention of human intelligence, but most often refers to the automatic processing of messages at an SMTP server, possibly applying anti-spam techniques. Filtering can be applied to incoming emails as well as to outgoing ones. Depending on the calling environment, email filtering software can reject an item at the initial SMTP connection stage or pass it through unchanged for delivery to the user's mailbox.
Postfix (software)Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. It is released under the IBM Public License 1.0 which is a free software license. Alternatively, starting with version 3.2.5, it is available under the Eclipse Public License 2.0 at the user's option. Originally written in 1997 by Wietse Venema at the IBM Thomas J. Watson Research Center in New York, and first released in December 1998, Postfix continues to be actively developed by its creator and other contributors.
Comparison of email clientsThe following tables compare general and technical features of notable email client programs. Basic general information about the clients: creator/company, O/S, licence, & interface. Clients listed on a light purple background are no longer in active development. A brief digest of the release histories. The operating systems on which the clients can run natively (without emulation). What email and related protocols and standards are supported by each client. Information on what features each of the clients support.
Anti-spam techniquesVarious anti-spam techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) as opposed to not rejecting all spam email (false negatives) – and the associated costs in time, effort, and cost of wrongfully obstructing good mail.
Email spoofingEmail spoofing is the creation of email messages with a forged sender address. The term applies to email purporting to be from an address which is not actually the sender's; mail sent in reply to that address may bounce or be delivered to an unrelated party whose identity has been faked. Disposable email address or "masked" email is a different topic, providing a masked email address that is not the user's normal address, which is not disclosed (for example, so that it cannot be harvested), but forwards mail sent to it to the user's real address.
At signThe at sign, , is an accounting and invoice abbreviation meaning "at a rate of" (e.g. 7 widgets @ £2 per widget = £14), now seen more widely in email addresses and social media platform handles. It is normally read aloud as "at" and is also commonly called the at symbol, commercial at, or address sign. The absence of a single English word for the symbol has prompted some writers to use the French arobase or Spanish and Portuguese arroba, or to coin new words such as ampersat and asperand, or the (visual) onomatopoeia strudel, but none of these have achieved wide use.
Outlook.comOutlook.com, formerly named Hotmail, is a free webmail service that is part of the Microsoft 365 product family. It offers mail, calendaring, contacts, and tasks services. Founded in 1996 by Sabeer Bhatia and Jack Smith as Hotmail, it was acquired by Microsoft in 1997 for an estimated $400 million and relaunched as MSN Hotmail, later rebranded to Windows Live Hotmail as part of the Windows Live suite of products. Microsoft phased out Hotmail in October 2011, relaunching the service as Outlook.com in 2012.
Internationalized domain nameAn internationalized domain name (IDN) is an Internet domain name that contains at least one label displayed in software applications, in whole or in part, in non-latin script or alphabet or in the Latin alphabet-based characters with diacritics or ligatures. These writing systems are encoded by computers in multibyte Unicode. Internationalized domain names are stored in the Domain Name System (DNS) as ASCII strings using Punycode transcription.
WHOISWHOIS (pronounced as the phrase "who is") is a query and response protocol that is used for querying databases that store an Internet resource's registered users or assignees. These resources include domain names, IP address blocks and autonomous systems, but it is also used for a wider range of other information. The protocol stores and delivers database content in a human-readable format. The current iteration of the WHOIS protocol was drafted by the Internet Society, and is documented in .
