@leetut: Did you know what a MMS is? Obviously there is a charge for every MMS you send, like for SMS (indeed it is usually much expensive for MMS). You are using your provider's network for sending MMS, like all the other mobile phone brands do. fMMS only provides a feature that N900 lacks, but it cannot make miracles. If you do not want to pay (and you have an accesible free WiFi), send an e-mail.

P.D. To delete the MMS access point, you can download fAPN and delete it.