Hi Dmitriy,
My name is Max Blinder, and I lead product management for Boxer. First, thank you for your feedback! Secondly, we are working on recently sent address caching for Android Boxer, and anticipate the will be available in the near future. If you aren't already, please feel free to work with your account team to join the Boxer beta program to access and test newly developed features before they are released to the general public.
Regards,
Max