Gmail is a free email program designed and operated by Google. Gmail was first introduced in 2004 by invitation only. Gmail customer service is only available by means of the help section of the program. You have to send emails to google for help and support.
Outlook is a free web-based email service offered by Microsoft, available as a part of the Microsoft Office suite. Although it is being used as an email application but you can manage your calendar, task manager, contact manager, note taking, journal, and web browsing using Outlook.
Yahoo Mail is a web-based email service offered by the American company Yahoo! The email service is free for personal use, and paid-for business use. Yahoo offers free support for both kinds of users through chat, email, and Phon numbers.