My ecas is updated with one more info today:
1. We received your application for permanent residence on July 14, 2014.
2. We sent you correspondence acknowledging receipt of your application(s) on September 16, 2014.
3. We started processing your application on October 3, 2014.
4. We sent you medical instructions on March 18, 2015. To avoid delays, please provide us the information requested in the letter as soon as possible. Please consider delays in mail delivery before contacting us.
5. Medical results have been received.
"To avoid delays, please provide us the information requested in the letter as soon as possible. Please consider delays in mail delivery before contacting us."
This is updated today. What letter are they talking about ?