This recent post on Consumerist about CenturyLink mailing an offer to an ineligible customer with prior issues is a reminder that all companies should have and maintain a Do Not Solicit list. The list should include who request opt-out as well as unusual situations like Seth’s. Use it for both email and snail mail.
Lesson: Save yourself some embarrassment -- have a marketing opt-out list. Maintain it and update it frequently.