An autoresponder sends an automated template message to the job seeker even before you have a chance to open their email. You can create different templates for different candidate types. Your company probably pays annual dues to at least one trade group in your industry, and probably many if you count memberships among individual staff. Many of these associations now have Web sites with career functionality. As a member, you may be entitled to have your jobs listed there free, as well as have access to resumes.
Most companies have no brand recognition with job seekers, especially relocating ones.
But candidates often check out the Web site for their trade in their state or region. Free trials for paid services. Some of the fee-based, Internet career services are worth the money. But which ones are best vary, based on the employer's industry, location, job title and even the time of year. The best way to evaluate them is to try them.