> The solution for people on dynamic addresses (typically with some > generic and non-matching PTR record, though I haven't checked yours) is > likely to relay out through your ISP's mail server.
because of the way the DNS is put together, PTR records cannot be relied upon. ownership of the DNS entries for a name are unrelated to the DNS entries for the in-addr entries for a set of IP addresses to which they map. this is all reminiscent of the nonsense of RFC1413
