We try to do that for email users, which is not the same as automatic bulk emailers via scripts, like phpBB. The email team constantly works to get DreamHost SMTP removed from blacklists but you have to know that this is a whack-a-mole game, there will always be hits and misses.
I work at DreamHost but I am not part of the email team, and I’m not speaking for them. When I managed my own SMTP servers I simply removed the possibility to send bulk emails from scripts because it was just too open to abuse. Think about the thousands of sites powered by WordPress, Drupal, Joomla, phpBB and co. get hacked every hour… all of them are implicitly authorized to send bulk emails. It’s a miracle to me that SMTP servers are still accepting any email at all
That said, the best solution I can offer is not to use DreamHost SMTP servers via scripts. The workaround I suggested is free (or very cheap) and very effective at email deliverability.
I suggest you also to open a ticket with DreamHost support because from the forum there is a limited amount of things we can do (besides relay this thread to the internal tickets).