Sales sourcing can vary by state,however, the trend in sales allocation, is to attribute sales receipts to the place where the goods are destined to be delivered. So in your case, if the sales are delivered to New York, they are New York sourced.
However, the overriding question still needs to be answered, just because you deliver to New York does this mean you have nexus in New York. If you do, then you would need to file a return there as well. If not, then the sales get thrown back to California.
Finally, you need to determine if the states you deliver to have an income tax or a pure franchise tax. Only an income based tax is subject to possible exemption based on Public Law 86-272. Franchise taxes are not bound by this federal law.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
