Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email entered limited use in the 1960s, but users could only send to users of the same computer, and some early email systems required the author and the recipient to both be online simultaneously, similar to instant messaging. Ray Tomlinson is credited as the inventor of email; in 1971, he developed the first system able to send mail between users on different hosts across the ARPANET, using the @ sign to link the user name with a destination server. By the mid-1970s, this was the form recognized as email.

Outlook.com is a personal information manager web app from Microsoft consisting of webmail, calendaring, contacts, and tasks services. Founded in 1996 by Sabeer Bhatia and Jack Smith, Hotmail 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.

Hotmail service was one of the first webmail services on the Internet along with Four11's RocketMail (later Yahoo! Mail). It was commercially launched on July 4, 1996, symbolizing "freedom" from ISP-based email and the ability to access a user's inbox from anywhere in the world.

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