How to Set Gmail as Your Browser's Default Email Client?

Please see this excellent article for the detailed steps.

 I would like to add several things from my experiments.

 1. In order to be able to see the Protocol Handler icon overlapping-diamonds , you have to log into your gmail account. 
2. When you are in step 2, if you accidentally click Ignore and then Done, the  Protocol Handler icon overlapping-diamondsis more likely gone from GMail. The only way I could make it back is to uninstall and re-install Google Chrome.
3. However, even after the Protocol Handler icon is gone, you may be still able to proceed by enter "Chrome://Settings/Handlers" (without the double quotes) in the address bar. Of course, if you did not choose 'Use Gmail' in the first step, you won't see anything here. You have to choose 'Use GMail' and click Done in order to be able to see mail.google.com as the site for mailto. 
4. It appears that Gmail is the only option here, at least in the version I am using (39.0.2171.99 ). You either have (None) or mail.google.com. You cannot have something else such as Yahoo Mail, Hotmail, or Outlook.
5. If you set the MailTo extension to Outlook, Live Mail, or Google Chrome via the Default Program option as described in an earlier post (see the snapshot below), you will get the same mail client form both IE and Chrome, If you do not use the Managing Protocol Handlers option.  

 However, if you really want to use the Managing Protocol Handlers option to set up Gmail as the browser's default mail client, the setup in Chrome will override the choice setup by the Default Program method. So you could have Outlook or Hotmail for IE, but Gmail for Chrome. Of course,  you can also have outlook (the underlying server could be Yahoo Mail depending your Outlooks setup), Hotmail, or Gmail for both IE and Chrome, if you just use the Default Program option.