Tutorials
---------

"SMTP with oauth for gmail." - Aug 2012
https://skroesbergen.wordpress.com/2012/08/22/smtp-with-oauth-for-gmail/

"GOOGLE, SMTP, AND OAUTH2 AUTHENTICATION" - Feb 2013
http://www.chargenevier.com/2013/02/google-smtp-and-oauth2-authentication/

PHP, SMTP, XOAUTH2 and Gmail - Feb 2014
http://www.boxuk.com/blog/php-smtp-xoauth2-gmail/


Creating a Gmail Token
----------------------

Google Developer OAuth 2.0 Playground
https://developers.google.com/oauthplayground/

Google Developers Console
https://console.developers.google.com/

Google Apps Security Settings
https://admin.google.com/AdminHome?chromeless=1&fral=1#SecuritySettings:

Account Permissions
https://security.google.com/settings/security/permissions?pli=1

Rereshing a Token
-----------------
How do I refresh my google_oauth2 access token using my refresh token?
http://stackoverflow.com/questions/12792326/how-do-i-refresh-my-google-oauth2-access-token-using-my-refresh-token



References
----------

Using OAuth 2.0 to Access Google APIs
https://developers.google.com/accounts/docs/OAuth2

Gmail Platform - OAuth 2.0
https://developers.google.com/gmail/oauth_protocol?hl=nl


OAuth Overview
--------------

Request Permission ->
<- Authorization Grant

Grant Code ->
<- Authorization Token

(Access Token and Refresh Token)


wp_mail() and Email in General
-----------------------------
Hacking WordPress Emails
http://glennmessersmith.com/pages/wpemail.html

The Importance of Content-Type Character Encoding in HTML Emails
http://www.emailonacid.com/blog/details/C13/the_importance_of_content-type_character_encoding_in_html_emails

The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)
http://www.joelonsoftware.com/articles/Unicode.html

How to Tell Who Supports SMTP TLS for Email Transmission
https://luxsci.com/blog/how-to-tell-who-supports-tls-for-email-transmission.html

JavaMail: Keeping IMAPFolder.idle() alive
http://stackoverflow.com/questions/4155412/javamail-keeping-imapfolder-idle-alive

Reach More People and Improve Your Spam Score: Why Multi-Part Email is Important
https://litmus.com/blog/reach-more-people-and-improve-your-spam-score-why-multi-part-email-is-important

HTTP Message Headers
http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2


PHP Resources
-------------
Why your PHP App NEEDS a Circuit Breaker
http://devzone.zend.com/1424/why-your-php-app-needs-a-circuit-breaker/