This should not be entered into lightly and the recipients should be aware of the swap. Consider a testimonial from the band or company that you are swapping with to increase the credibility of a mailing from an unknown entity. You should also ask the other party to do the same. Ideally, you should only work with those that you feel comfortable recommending. Treat your list well and they will spread the word.
Referrals are a great way to acquire new prospects.
As you send out mailers or emails mark the records that come back as undeliverable. I have a field that I mark, Bad Address if mailers come back, and Bad Email if emails come back. When I do mailings, I have the search criteria OMIT those particular records so that I don't waste postage, or time searching records that I've already marked as bad email . I would recommend this over deleting the records so that if you get updated info you can simply amend your current record rather than creating a new one. Every so often, send an email to all your bad addresses asking for people to get back to you if they receive your message.