What you really need to do is run a local MTA which can deliver to a local domain. This is the only way that you'll be able to adequately test the mail() functionality while on the road and not connected to the internet.
To do this you'll need to at least install a MTA additionally.
Personally I always write a wrapper for mail() which does some more checks:
- If in dev mode, it sends all emails to the same address (configurable)
- Performs various checks against newline-injection in headers
- Applies various misc headers I want to add (e.g. content-type)
You could also make this custom mail function wrapper check a constant to disable mails altogether, although there will be a lot of cases where you really want mails to arrive so you can test it.
Mark