Our users are interested of a possibility to restrict "To" field to a certain number (configurable) of unique recipients to avoid mistakenly sent e-mails to multiple recipients.
We mostly use "Bcc" field for the purpose of hiding recipients from each other, but sometime due to human mistake "To" field is being used and it can cause a lot business troubles at the end. That is why we look for a ways to avoid these unpleasant situations.
Let me know if this can be technically achievable and if, yes, potential ETA would be great to have.
In any case, we are supper thankful for your great add-on and the constant improvements you add to it.