This simple module adds a few additional mail icons to the chatter. There are extra colors that amplify a certain status: if the email was sent, bounced, not sent (server error etc.) or planned. There's also an additional email information when clicking icon, so the small pop-up window shows up. Failed emails have extra information about Status in Sending Failures Wizard.

Also, this module allows you to set up a note about newly created meetings, which will automatically show up in the chatter, however this requires code adjustments, see the link with an example code below or install mail_message_icon_demo where such set up has been configured with recruitment app.