We are trying to get someone - anyone - at Bluehost to respond to our questions as to why they've blacklisted some of our addresses. It's unclear why they have done this. Our two best guesses, in the absence of any assistance from them, are: They have some filtering that's seeing email come in, deciding it might be spam, and then blaming our IP addresses, even though we're just relaying it on after filtering. Or they see a large number of messages coming from one of our addresses, and the rate causes them to blacklist the sending IP address.
Regardless of why they're doing this, we understand that it's very frustrating.
If you receive any information back from them, if you get anybody to even talk to you, please let us know, so we can try to follow up with that person. We cannot seem to make any progress with them at all.
Please know that we're doing all we can here.