title: Too many Gmail API push notifications when sending emails with many large attachments
body: <p>I'm using the Gmail API (With the Google Cloud Platform) to send push notifications to my server. This mailbox is never actually accessed by a user, it only exists for the purpose of sending push notifications to a route on my server that retrieves the latest email from the mailbox.</p>
  
  <p>Everyday, I have a cron job that renews the <code>Users: watch()</code> on this email address. It's only one email address associated with a single topic in the Cloud Console with one <code>push</code> subscription to my server. My controller then calls <code>Users.messages: list</code> to get a list of recent emails, followed by <code>Users.messages: get</code> to get the most recent email with all attachment IDs/filenames, and finally <code>Users.messages.attachments: get</code> to get each data for each attachment.</p>
  
  <p>I've noticed that when I send emails with lots of attachment data (25 Mb of image data for instance), I start receiving a series of push notifications, each with the same <code>message_id</code> and timestamp in the data sent with the push notification POST request. For now, I'm dealing with this by saving the <code>message_id</code> in a cache for a little while to prevent my server from reacting to a single push notification more than once.</p>
  
  <p>Although my solution works nicely, I'm curious if anyone else has experienced a problem like this, or whether this is a bug in the Gmail API or Cloud Platform. Any help or advice is appreciated!</p>