This plugin incorporates Gmail API for WordPress comment license.
Refer the following link to know more Registering email..
Upload gmail-inbox-action folder to the wp-content plugins directory.
Activate the plugin through 'Plugins in WordPress..
For proper working you need to make sure that your emails DKIM signed.
Register with yahoo http goo. gl siU783..
What is DKIM signed emails.. DKIM certificate are used to avoid spamming of mails you can install it on. server using this Setup DKIM...
Google keeps track of emails implementing Gmail actions to avoid spamming...
Register the email from which server sends the email to make sure the button is displayed.....
Browse the code recheck out SVN repository or subscribe to the development log RSS....
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