Hello, We use reject_unknown_client to fail messages from hosts with no rDNS. We have a situation with the host 216.163.249.229, which give the following results:
NOQUEUE: reject: RCPT from unknown[216.163.249.229]: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [216.163.249.229]; There actually is reverse DNS for this address... 239 PTR records! using 'host' returns them all, with a warning: ;; Truncated, retrying in TCP mode. .. and then all the results So I guess the result is so large that UDP cannot contain it, and within postfix the TCP method either isn't being tried or isn't working. Is this a problem with my resolver or something I can fix in postfix? The lookup does work on this machine using 'host' with the above error. -Aaron
