Delivery to the following recipient failed permanently:

     marascnd@potsdam.edu

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain potsdam.edu by mx1.potsdam.edu. [137.143.110.103].

The error that the other server returned was:
553 sorry, this recipient is not in my validrcptto list (#5.7.1)