Gmail launched on 1 April 2004 as an invitation only beta release and became available to the public on 7 February 2007. To this day the service remains in beta status and has tens of millions of users.
- For viewing unread messages in your inbox, you need to use the combination in:inbox is:unread in the Search function. 
- How do I enable POP?. Google (2007-09-03). Retrieved on 2008-06-01. “You can retrieve your Gmail messages with a client or device that supports POP, like Microsoft Outlook or Netscape Mail.”
- How do I enable IMAP?. Google (2007-10-23). Retrieved on 2008-06-01. “You can retrieve your Gmail messages with a client or device that supports IMAP, like Microsoft Outlook or Apple Mail.”
- Google opens Gmail to all, retrieved 27 March 2007
- Swartz, Jon (2007-11-22). Despite filters, tidal wave of spam bears down on e-mailers. USA TODAY. Retrieved on 2008-06-01. “For a start, tens of millions use Google's Gmail because it was designed with built-in spam defenses.”
- Perez, Juan Carlos (2007-12-10). Google Disables Some Gmail Accounts by Mistake. PC World. Retrieved on 2008-06-01. “Hohne said the mistakenly disabled accounts affected "a small fraction," well below 1 percent of the tens of millions of Gmail users.”