Hotmail email responce notification text message

[Guest rfsteel]

I've got a SPV C600 running I-Mate ROM 5.1.195.14847.

Today I noticed that after sending a email from my hotmail account on my handset, that when the recipients responds to it, I get a text confirmation of the message from 80090113674.

I presume that Micro$oft are charging me for this message, so would like to know how I can disable it, as I can't find an option for this.