Non Disclosure Agreements for Composers
So-called non disclosure agreements (NDA) are quite common practice in the media world. Some companies/clients handle them very strictly and generally put every project under rigid NDAs (sometimes going as far as having fake cue names on score sheets so that nobody from the orchestra knows what they are playing for) while other companies have a very lose policy on that.
In any case, you should stick to these agreements as it can cause nasty juristical consequences if due to you being a leak sensible information about the project gets to the public. In such cases you should also be sensitive about how you behave. For example sending out files to the company by an obvious public http link (http://www.mydomain.com/secretproject.zip) is not the greatest idea.
In such cases rather a password protected folder or ftp access should be your choice to deliver. Just develop a sensivity for these issues as some companies are really very picky on this.