Our delivery guys told me the reason for this is that at the time we
saw the Hard Bounce we also saw that the address had had click/opens
activity. Apparently when that's the case and we see a hard bounce we
simply remove the activity scores we have and record the hard bounce,
but do not remove them from the list in anticipation that they
actually just have a crappy mail host. On the next send if they hard
bounce they are correctly removed.
Looking at that address, they've hard bounced 3 times in the past 6
months yet have not been removed which means it is a poorly performing
mail service since they are receiving and acting upon subsequent
campaigns.
jesse