Hi Dan,
Unfortunately, there is not a setting to disable the zoom function.
One option might be to change the address in your spreadsheet to be more generic - rather than address, city, state, zip you could simply do city, state and zip. This will only be effective if you have less than 2 addresses per city.
We'll add this to the list of enhancements moving forward. In the event you need the functionality sooner rather than later, and are open to co-funding the development effort, please shoot us an e-mail at help@mapalist.com and we can discuss further.