I have a customer that has blocked Marketo's IP addresses (very strict guidelines, per their industry). They wanted to get our emails, but could really only do it from the IP level -- but if they whitelist our range of IPs, then they will get ~1000 other companies that share the server. It's not worth getting a dedicated ip for just one customer... I found some sort of regex whitelist, but they said they can't do regex whitelisting. Is there really no other alternative? I even met with the deliverability people from Marketo at Summit and they seemed to not have seen this much before -- which baffles me. Nation, help me -- tell me what's up!?