Trulia doesn't host email addresses. The addresses you're seeing are generated by our email proxy which we use to prevent spam and help us track quality leads and help ensure that the agents who receive leads are responsive. Many companies Craigslist and LinkedIn already use this kind of technology for these same reasons.
When you reply to these emails, they will still get delivered to the right place. However if you need to access the real address of one of your leads, you can do so in your My Leads inbox.
Let us know if you have any more questions about this, or anything else, and have a great evening!
I saw this too on a couple of my leads last week. I came across the following customer reps contact informaiton, maybe if you contact him directly he can share with you what happened and then you can share here with us! :)
Community Manager, Trulia Voices