Hi venakt,
the main source of generation to mail bcc,cc is CL_CMPIC_MAIL_WRAPPER_SC class in that go to ONNEW, ONREPLY or onforward.. this are the methods which are trigger when ever you pressing any button like reply,new,forward.. so debug in to that methods you may come to know where you will get that address.. you can change the too,bcc,cc address also observe this sc_icmail_2_maildata method too.
ex code: this method will give the too email deatils in lr_mail_data. in loop we are assigning too data..
sc_icmail_2_maildata(
EXPORTING is_ic_mail = currentmail
it_ic_mail_attachments = currentattachments
IMPORTING er_mail_data = lr_mail_data ).
LOOP AT lr_mail_data->to ASSIGNING <fs_address>.
lv_default_from = find_matching_outgoing_address( <fs_address>-address ).
IF lv_default_from IS NOT INITIAL.
EXIT.
ENDIF.
ENDLOOP.
so try to debug the methods which i have mention above class.
Regards,
Srinivas.