A domain with a checkered past
I work at a company that purchased a .com domain around a year ago, and it uses this domain for its web site and e-mail now. However, the previous owner had a site (last online several years back) on the domain which was pornographic in nature. The site is now G-rated and has no adult or otherwise offensive content whatsoever.
E-mail blacklists have not been a problem, but some web content filter blacklists seem to block the site. We've sent e-mails to various providers, such as Sophos, that we have found to block the site to request review and removal.
These requests usually get us removed eventually, however, sometimes it is difficult to determine what the blocking engine is. For example, recently someone reported that if they go to the web site on a Virgin America flight, it redirects to the Virgin America homepage as if a content filter triggered a redirect. It's hard to tell what mechanism they're running.
How to get unlisted?
My question is: What is the best way to approach getting removed from content filter blacklists? Are there services/consultants that specialize in this? Or shall I truly be reduced to a game of whack-a-mole trying to hunt down and e-mail these blacklist/content filter operators as we notice problems?