Hi @Stas ,
Do you mean that you want to filter the incoming emails based on the “To” field?
According to your description, I have started the flow from the template, setting To field as my own email address.
However, as you mentioned, the flow won’t be triggered once To field is filled with certain email address.

I will do more test and try to involve more resources into this issue, will back to you once I got any updates.
Best regards,
Mabel