To email multiple listings, here is what you do:
Go here to login with your email address and password:
http://www.homeexchange.com/login.php
If you have forgotten your password, you can retrieve it via email from that same page.
Once you Login to the site with your username and password, you will end up at the "Your HomeExchange.com Account" screen.
You will see on this page a link "View My Saved Listings" just below the bold black title "Exchange Helper". Once you click "View My Saved Listings" you will see all the listings you have saved.
On the bottom left of each listing display you will see a small checkbox that says "Contact this listing (see email form below)". Click the mouse in each box for each listing that you wish to contact.
Scroll down and fill in the email at the bottom of the page. When you click send the email will be sent to all the listings that you have checked.
Note: To add to your saved listings click the blue link that says "Save Listing" displayed on every listing page.