Tracking marketing done 'Outside of Tessitura' for members

Hi everyone,

Relatively new with Tessitura (went live in November 2017!) and we are slowly adding new processes so that we can store more and more data on our members. We currently send out invitations, renewal letters, newsletters, etc... and are looking for a way to track open rates, RSVPs ,etc... right in Tessitura even though we send these out with other systems. 

Any ideas or best practices on how to do this?  We have volunteers who love data entry who can enter this all for us...just need to know where to store it and what this looks like!  Looking forward to hearing back.

Of note, we aren't live with TNEW yet, but will be in the next few months...just something to keep in mind.