E-mail opening data connection, despite being connected by WiFi

[Chick3n]

Hi, I'm using Energy rom 21914.Sense2.5.Cookie.GTX.Aug.24 in my sprint TP2 since the release and today I'm experiencing a problem:
when connected by WiFi (with max strenght signal also) and trying to send or sync my e-mail, the phone will open a data connection instead of using the wireless one already connected!
The problem is that I have a very very limited data plan and since I'm usually connected by wifi this sucks...
The other apps, weather/opera/etc keep on the wifi connection and the only thing that opens a new data connection is the mail - by the mail tab and by windows live.
I also know that I could turn off the data connections with "Data Controller" or so, but I'm really upset because all was going well until today and now with no apparent reason it occurs this stupid thing!!
Anyone experiencing this or having a solution to get it back to normal?