Who did you get an email from? Was it school administration? Teachers? Maybe you can meet with the teachers in person?
I have similar behavioral issues w/ my kids when they talk to their dad (never mind when they visit their dad - that is a whole 'nother level of behavior issues) - and it always helps if I talk to the teachers in person. It sort of "humanizes" it for the teachers.
And, of course you know this, but DOCUMENT all this!