I have been getting bounced emails and notices on these from Hotmail, Hotmail.uk, Live, and Live.uk since about March 5th.
I've filed three tickets and checked my domain for blacklisting, and attempted to go through the "I am not a spam bot let the emails through" with Hotmail/Microsoft, but am unable to do so since they detect dreamhost's abuse, postmaster and other email addresses instead of my domain's. They send the form to those and, despite any additional instructions I place in the window given, I have not seen or heard anything from Dreamhost regarding this issue.
Also, the emails continue to bounce.
I have also attempted to set up SPF records via the procedures outlined in the wiki.
This is a huge issue because my forum members are not getting notifications.