Third level .name email forwarding

I have a third-level .name domain, chris.boyle.name. These have the unusual feature of providing an email forwarding alias on the second level: chris@boyle.name. Note that I don't own boyle.name, that's shared, and the MX for it is e.g. mx02.nic.name (at Verisign). Customers configure the destination for such a forwarder at their registrar, who passes it on to Verisign, using this EPP extension: http://www.verisigninc.com/assets/email-forwarding-mapping.pdf

I'm looking for a registrar that supports this weird feature. Does DynDNS support it?

(Background: the feature worked at my first registrar, who has since gone out of business, and then it worked for several years at Gandi, but then abruptly broke earlier this month and nobody knows why. Since then I have tried two other registrars, both of whom claimed to support the feature when I asked them before transferring, and then admitted that they could not support it after I had transferred. Needless to say I'm not happy about that.)