Krishna Murthy a écrit : > Hi, > > I have reject_unknown_client in my smtpd_recipient_restrictions and > have 2 questions regarding the working of this option. I looked up the > documentation, but would love to cross check my understanding with other > users. > > 1. > > I have noticed that the following scenario results in rejection with > error - > > 450 4.7.1 Client host rejected: cannot find your hostname > > 1. A host connects to my postfix server from IPAddressA > 2. IPAddressA has a proper PTR record pointing to HostnameA > 3. HostnameA has an A record and points to IPAddressB > 4. IPAddressB does not have a PTR record. > > The above behavior suggests that postfix expects a PTR -> A -> PTR -> A > mapping. Is my understanding right? > > Or is PTR -> A -> PTR adequate? >
IP -> PTR -> A=IP in case of multiple PTRs, only the first is used. if there is a round robin, then you should guarantee the match above for all PTRs, or you'll have a mismatch from time to time. Multiple A record (last step) are ok. > > 2. If IPAddressA points to HostnameA and HostNameA points to IPAddressB > ( not to IPAddressA), should that be considered as an unknown_client and > eligible for rejection? > it's "unknown_client", but this is too aggressive today. you'll have to wait until the big gorillas (aol, google, ... etc) enforce this.
