Welcome to Trulia Voices and thank you for your question. Postlets isn't restricted in the number of photos they can include in the listing data feed they send to us. You may want to contact Postlets to ensure that they are including all of your listings photos in that feed. If they are doing so and we are not displaying all of those photos, they can contact us so we can investigate on our end.
Also, please note that photos are editable for all listings at this time. If you claim your listing you will be able to edit the photos associated with it in the My Listings section of your account. You can not only add and remove photos; you can reorder them as well.
I hope this information helps you. If you have any other questions, please let us know.