Best way to mark leads inactive?

Best way to mark leads inactive?

Currently our team has almost 14,000 active leads in the system which have been accumulated over many years - some purchased by lists, some from sales people who have moved on etc etc.

Of these, I believe there are less than 1,000 up to date, valid, quality names.

However, it feels counter intuitive to start deleting leads from the system (we may want this data should someone come back to life later). So we've decided we need to "archive" these people in some way. Separating them from the fresh leads (and anyone new we add to the system), in case our team wants to make some cold calls.

How best to accomplish this?

My first thought was to simply create a tag called "inactive" and apply that - however it looks like I am only able to work with 100 leads at a time via any given method.

Hoping for a solution that is clearly visible to sales (so they don't target someone who we know is unqualified), easily sorted ("remove inactive leads from view").

Thanks