Removing inactive contacts

Hi ​@Jeff Gang I’m not familiar with your particular data or the size/age of your database but here’s where I would start from a priority list: 

yes to your suggestion of unsubscribed and no donation history. 
Bounced emails - if none of these have donated within 2 years, I would delete. If they have donated, I would attempt to fix. 
Unengaged contacts - contacts with no donation history and have not opened an email or engaged with your organization (Advocacy form, event attendee etc) in the past 2 years. 

Depending on the age of your data...I once worked with a customer who imported donations from 10+ year ago but they had no email addresses for the majority of these contacts and they didn’t send that much direct mail  + more than 2/3 of these donors had not donated within this decade. I advised them to remove these contacts if they had no giving history within the most recent 4 years. 

Others might recommend trimming to only keep those  that have engaged within the past 12-18 months but again, depending on the size and age of your data and how much you are wanting to trim that’s really up to you!