The term mailto refers to the hyperlinks that are used instead of http:// so that if you click them it will open a new email for you to compose instead of a link to a website.  


For Chrome Browser Users:


Step 1 - Open Gmail in your Chrome browser and click on the Chrome menu icon (Top Right.)

Step 2 - Click "Settings" towards the bottom.


Step 3 - Click show advance settings link at the boom of the screen.



Step 4 - Click the content settings button under privacy.

Step 5 - Find the handlers and click the manage handlers button.

Step 6 - Then from the Dropdown choose Gmail, click done. And your done.  Go test it out in your CRM.


Notes:  If this doesn't work for you or the protocol handlers area is blank - try installing google's mailto download from the Chrome Web Store.

Notes: if this doesn't work try this

 (Found more info at: https://productforums.google.com/forum/#!topic/chrome/sPhxiTQlf4s)

ATDP said:

I had the missing mailto: protocol handlers problem and wanted to add them back in - Fix_Chrome_Please's link worked for me.

To summarise and tweak what's on his link, try the following:

For mailto:
- Make sure you are logged in to Gmail and the active window is your main Gmail page (or nothing will happen).
- Copy/paste this into the address bar:
javascript:navigator.registerProtocolHandler("mailto","https://mail.google.com/mail/?extsrc=mailto&url=%s","Gmail")
- Add the javascript: to the front again if needed, because when you pasted it, Chrome probably trimmed everything before and including the colon. Then hit enter.

It also works for webcal:
- Make sure you are on your Google Calendar page (or nothing will happen).
- Copy/paste this into the address bar:
javascript:navigator.registerProtocolHandler("webcal","https://www.google.com/calendar/render?cid=%s","Google Calendar")
- Add the javascript: to the front again if it got automatically trimmed. Then hit enter.


We don't have the situation here where the popups don't appear at all on our initial installs, does this fix work for those cases too?


Note: Recent Feedback on your browser mailto: client also suggested trying

Wanted to let you know there is a much easier and better way to do this, found it when I went to download what you suggested, here it is (I run Chrome Version 49.0.2623.110 (64-bit) on Apple Mac running OS X El Capitan version 10.11.3 and it worked like a charm.

 

I did however find a way to get chrome to handle mailto without a plugin/extension:

go to gmail website, in the far right of the address bar is an icon looking like two overlapping tilted squares (next to the star favourite icon), click this and select "allow gmail to open all email links" and voila!


Note:  If none of the above solutions work we suggest consulting with an IT expert to help you with this.