Add e-mail read status information through image in HTML mail
It would be nice to have more information in Chamilo about the fact that one person has read a message (even if it's not in the social network but in the e-mail sent).
This is usually done by inserting an image with a special code/hash inside the HTML e-mail. When the user loads the mail, the image is loaded and "pings" the server, making it possible to register the fact that the e-mail was opened.To do this, we should do the following:
- declare a common script that answers to the ping (like main/messages/ping.php) that takes only a hash argument and returns a one-pixel image
- add a mail_read_hash field and a mail_read_date default NULL field to the message table (only set the date when there is a ping)
- change the function that registers a message to add an <img src="portal.com/main/messages/ping.php?hash=ezaqqzfeqdq2324zdqz" /> somewhere not too visible