Some customers are seeing intermittent errors when attempting to upload a new image or insert an image into their email. While we look into getting this fixed we have found if you try to reattempt your previous action, the image will be visible. We apologize for this inconvenience.
At this time we do not offer that type of query on the lists collection, we'll take a look and see what kind of feedback we get for this. Regardless of implementing this or not, the limit on how many contacts can be queried per HTTP Request to the API is 50 per request. For you to get the entire contents of one list of 1000 contacts, for example, it would take 20 HTTP Requests, each of which would have to be processed for the next URI for collecting them. Because of this limit, it generally is more overhead on both our servers, the bandwidth of everyone and your program to process contact retrievals of any modest size using this method. I would recommend using the Bulk Activity collect for all these types of queries, the files generally are ready in 5 to 10 minutes and require much less processing overhead on both your program and our system.
The Constant Contact API now includes an API which traverses the members of a Contact List. Please see this reference on the Contact List Members Resource for more information.
Note that if you have large Contact Lists, you should consider using the Activities resource. The Activities resource submits an asynchronous batch job which, when completed, returns all the members of the list in a single report . The Contact List Members resource responds immediately with the first page (ie. the first 50) of Contacts in the identified list.