Touchpoints have two options when it comes to Timings:
New Additions only
Existing and new additions
When pausing a touchpoint that has the Timing 'New Additions only', you will have to go through the following steps to ensure that it doesn't retroactively send emails once it has been made live again:
Go into your touchpoint and make sure it's in 'draft'.
Go to step 2, Timings.
Change the timing from 'New additions only' to 'Existing and new' and click save. Make sure the touchpoint is still in 'draft'.
Once you have clicked save, change the timing back to 'New Additions only' and click save again.
Your touchpoint will now only send to students who join after it has been made live. You will have to do this for each one.
What this does it essentially 'reset' the touchpoint timing and allow it so that the touchpoint will only send to students who join the workflow after it has been made live. As the touchpoint has already been made 'live' previously, by 'reseting' the timing the touchpoint will only send to students who join when it is next made live. It won't send to any students who joined whilst it was in 'draft'.