There are different types of email alerts that Trulia sends out, so there are a few places for unsubscribing from alerts.
Go to your profile drop down menu in the top right hand corner >> Email Preferences. Once that screen is open, you will see the option to "Edit" the following sections.
Saved Searches: Once on this page there is an option to delete individual searches along with the option to Delete all.
Homes You're Following: Once you are on this page you have the option to Manage alerts or
if you no longer wish to receive email alerts for a particular property, no problem. Simply remove it from your Favorites on this page.
Trulia Voices: Once on this page there is the option to delete topics you are following.
Trulia Weekender: Once on this page there is the option to delete individual areas you're following or Delete all.
Email Communication: Here you can uncheck the box for any notifications you do not want to receive.
Consumer Care Advocate