Most recently, AOL has tightened their DMARC policy to outright "REJECT":
It has been on the horizon for quite a few years, but now it's become imperative/urgent that Imail is finally brought into full compliance so that the "forwarding" (either using an Imail "ALIAS" or with the "forward" option for a mailbox USER) is implemented as a proper "sender-rewriting" or at last "remailing", rather than the simplistic "forwarding" scheme.
People with "vanity" domain/email addresses, who are using forwarding in Imail are increasingly having problems because naturally the "from" IP address (the Imail Server) is NOT a permitted sender in the final recipient mail system (such as Gmail/AOL/Hotmail, etc.). In the major open/free mail systems, one could have been using one of the SRS plug-ins (http://www.libsrs2.org/srs/srs.pdf) all this time, however, with a proprietary/paid-for system like Imail, we have to be able to depend on Ipswitch to keep the software up to date, in return for the annual fees collected.
I think enough time has passed that this should be fixed by now - but the recent actions of major email services now add to the urgency!