Remarkety's Magento plugin implements "push notifications" to Remarkety and informs our server whenever someone signs up to the Magento newsletter, products change their prices, and more.
Sometimes, a re-install or upgrade of the Remarkety plugin can cause the API key to become out-of-sync and cause queue message to fail.
To solve this issue:
1. Go into your Remarkety dashboard -> Account Settings -> Connection tab
2. Copy the API Connection Code:
3. In a new browser tab, login to your Magento admin, and go to to: Remarkety -> Remarkety Configuration
4. Paste the API Key into the API Key field, and click Save.
5. Back to Remarkety, test the connection again by clicking "Test Connection"
6. If everything is OK, go back to Magento, and resubmit all of the queue items by using Select All -> Resend -> Submit