Yes but @Josh the IP address you are sending from at the time of your test is not necessarily the one originally used to send to the recipient. Unless you have a sample from that original send, you don't have a reliable source -- and it is frequently the case that .123 can be blacklisted while .124 is not. If you want to be reliably whitelisted by a recipient you need to give them all the ranges. That list of IPs is provided by Marketo specifically for whitelisting and/or forensics.