Answer: gmail

AnswerCrossword Clue
GMAIL

Web-based correspondence service

GMAIL

AOL alternative

GMAIL

Google Apps component

GMAIL
Web-based service with millions of users
GMAIL
Big name in Web-based correspondence
GMAILFree Web-based correspondence service
GMAILPriority Inbox offerer
GMAILTech service with over half a billion users
GMAILOutlook alternative
GMAILService with nearly two billion users
GMAILApp with an envelope icon
GMAILService with more than 1.5 billion users
GMAILOnline service introduced in 2004
GMAILService launched on April Fool's Day in 2004
GMAILYahoo alternative
GMAILService with more than a billion users
GMAILCommunication service since 2004
GMAILAlternative to AOL or Yahoo