Squashed commit of the following:

commit 566d14ac539457a968b18980dd9bc6d0e4d6d5e5
Author: Sam Shull <sshull@zendesk.com>
Date:   Wed Aug 7 12:52:05 2013 -0700

    Don't queue unsubscribes

commit 6f81eb0221d6056c346c90ba802552b1d77ce4bf
Author: Sam Shull <sshull@zendesk.com>
Date:   Wed Aug 7 11:10:00 2013 -0700

    Do not queue memorized messages for performance