Comment 3 for bug 1225063

The package involved is indicator-messages, so if you would like the "envelope" icon to disappear altogether you could just remove the package:

sudo apt-get remove indicator-messages

My problem is that I am using a mail client, so I need the indicator, but I don't want any of the status menu items (online, offline, etc). I think I have uninstalled all of the packages providing instant messaging, but the status items are still there. This was not a problem in the previous version 13.04. I found some instructions how to produce a patched package which hides the status icons:

http://askubuntu.com/questions/185021/how-to-remove-or-hide-chat-status-icons-from-messaging-menu

However, there should not be a need for that: they should not be showing at all if there is no need for them.