Recently, AOL Email and selected other domains were non-deliverable. The same addresses have been deliverable for several years. Somehow, AOL was responding to an IP on my assigned IP assignments that was / is not being used. My belief is that a configuration issue arose in a recent incident when my sever was apparently 'hacked' and NEXCCESS helped discover and correct. At any rate, the NEXCESS support team is always gracious and helpful. Brett in particular was able to bring the errant IP association into line and has probably offered that I can make an even better setup and IP assignment for my Email Marketing Campaign Software