Donating your services or products to a charitable organization is a good way to give back to the community and effective way to build your company's relationships. As you would like to say yes to all request, it is just not possible. Here are a some ways your company can handle these request:
Create a dedicated page on your website to handle charitable contribution request. You can direct visitors to a specific page to submit a form request. This form allows you to setup an automated response email for every submitted form request.
This dedicated page can also contain your step-by-step procedures for handling charitable donation requests. For example, once a form is submitted, it goes to a committee for review and then the organization will be notified whether or not their request can be fulfilled.
This page is a good place to highlight all the charitable organizations and events you have already sponsored. Include testimonials from the organizations you have supported on this page. Showcasing your contributions will show the community how supportive and involved you are which will strengthen your brand and reputation.