Turning off check stub notifications in Bulk

We are bringing on 3 New Clients in the middle of 2026 and need to get their historical data over to their Portals. (Paystubs + W2s). I try to sync the past Paystubs and all the Employees received an email alert for each one! The Client doesn't want so many emails going out and now I can't turn off the check stub notifications in Bulk I have to go through each individual Employee to do that which is wasting a lot of time. Support tried to switch them over to Onboarding mode and they still received the emails. This is very frustrating when trying to just simply get historical data over.