FYI, after some testing it seems like a very simple solution to having your email address compromised is to simply change your settings so you aren't sent an email every time you receive a personal message.
The way this exploit works: When you CC people in a PM, an email is also sent to everyone who was CC'd in it notifying them of the personal message. In that email itself, people are also CC'd, and since it's not a blind CC you can see the emails of everybody who was CC'd in the PM. If someone in the targeted group used mailinator, you can do a password reset request and then access their mailinator inbox.
tl;dr don't use mailinator, and if you want to protect your email address turn off PM email notifications