You can assign multiple WebHooks to a single account, one WebHook to multiple accounts, or, simply, one WebHook on an individual account. Required parameters are the URL that Context.IO calls when a matching message is found (callback_url) and a URL Context.IO can call should the WebHook fail (failure_notif_url). There are also a number of optional parameters that will filter the messages that you want by specific criteria (as noted above), such as the “to” field (filter_to), “from” field (filter_from) the subject line (filter_subject), and more. You can even create a WebHook that notifies your app when Gmail labels a message as “Important” (filter_new_important). And of course, we have attachment specific WebHooks that will let your application know when a file has been attached to a message (filter_file_name) or if any revisions have been made to a specific file (filter_file_revisions).
Check out this post about some of the WebHooks we've integrated in v2.0 of the Context.IO email API. No more need to constantly poll our API for relevant messages for your app. Get automatically notified when messages meet your app's criteria.