@cadusilva I couldn't wait and ended up migrating over the other domain today too. One catch I didn't anticipate is that whatever you use as the MX record needs a matching PTR record, and you can only have one PTR, so all your domains will have the same MX (which doesn't even need to be in those domains, it can be associated with a 3rd unrelated domain). The only downside of this is that this MX host will be used everywhere for auto configuration, which is a bit annoying.