Do you own or will you be setting up a Craigslist Proxy soon? If so make sure you get IPs from as many different C class IP ranges as possible. C class IP ranges aren’t talked about much, but by not making sure you are using IPs on your proxy server from different C class IP ranges you are opening the door to be blocked by Craiglsist.
Their are 4 main ranges for IPs, A B C and D. Ranges are used to keep track of and log the network and ID of the network. Everyone on the internet is assigned an IP which is used to identify them while they are online. The most common method used to change your IP is by reconnecting to the internet, but more often than not it is still within the same IP range. This allows companies and other people to more easily identify your activities as even after changing your IP, it hasn’t changed enough so that one could make assumptions or try and track patterns of activity between your new and old IP. This could also very well be used by Craigslist in their attempts to log use of Craigslist by people posting ads. Using different C class IP ranges on your proxy server would definitely make it much harder or almost impossible for Craigslist to do this.
As mentioned above, using IPs in the same C class IP range may make it possible for Craigslist to detect your activity even though you could be using several different accounts (as the new IP you are assigned has not changed enough to make you look like a completely different user from somewhere else). This very same concept of using different C class IP ranges applies to proxy servers and is something you should pay great attention to. Usually, IPs on proxy server are within the same range, which is what you do not want. Anonymity is very important for anyone posting on Craigslist, so make sure your Craigslist Proxy has different C class IP ranges if possible.