Re: [courier-users] Classless reverse dns and mail delivery
On Thursday 03 September 2009 19:52:07 Joseph C. Lininger wrote: Good afternoon, This is done in a way such that a reverse lookup looks a little different than normal by introducing an extra CNAME lookup step (see example below) and I'm simply wondering if I could run into problems with certain smtp servers when delivering mail to them from my courier server (slash.sentinel.dk). You should have no problems as long as the resolver used by the mail server you're delivering to handles it properly. To my knowledge, all of them do. A cname is a perfectly reasonable response to a request for a ptr, and should just cause the resolver to restart the lookup with the name specified in the cname response. It results in some extra overhead, but that's a problem any time you use cname records. Thanks. What I was hoping to hear. :-) Best regards, Frederik Dannemare -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
[courier-users] Classless reverse dns and mail delivery
Hi Sorry if this is slightly off-topic. For the first time I've had to deal with classless reverse dns for a /25 subnet assigned to me. Thus, I've asked my IP provider to delgate rdns for the entire /25 to my dns servers. This is done in a way such that a reverse lookup looks a little different than normal by introducing an extra CNAME lookup step (see example below) and I'm simply wondering if I could run into problems with certain smtp servers when delivering mail to them from my courier server (slash.sentinel.dk). frede...@fda-lenny:~$ host 95.128.25.121 121.25.128.95.in-addr.arpa is an alias for 121.0.25.128.95.in-addr.arpa. 121.0.25.128.95.in-addr.arpa domain name pointer slash.sentinel.dk. frede...@fda-lenny:~$ dig -x 95.128.25.121 ; DiG 9.5.1-P3 -x 95.128.25.121 ;; global options: printcmd ;; Got answer: ;; -HEADER- opcode: QUERY, status: NOERROR, id: 49385 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0 ;; QUESTION SECTION: ;121.25.128.95.in-addr.arpa.IN PTR ;; ANSWER SECTION: 121.25.128.95.in-addr.arpa. 86394 INCNAME 121.0.25.128.95.in-addr.arpa. 121.0.25.128.95.in-addr.arpa. 10794 IN PTR slash.sentinel.dk. ;; AUTHORITY SECTION: 0.25.128.95.in-addr.arpa. 4918 IN NS ns01.sifira-ums.dk. 0.25.128.95.in-addr.arpa. 4918 IN NS ns02.sifira-ums.dk. ;; Query time: 0 msec ;; SERVER: 192.168.1.33#53(192.168.1.33) ;; WHEN: Thu Sep 3 16:34:37 2009 ;; MSG SIZE rcvd: 144 Best regards, Frederik Dannemare -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] Classless reverse dns and mail delivery
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Good afternoon, This is done in a way such that a reverse lookup looks a little different than normal by introducing an extra CNAME lookup step (see example below) and I'm simply wondering if I could run into problems with certain smtp servers when delivering mail to them from my courier server (slash.sentinel.dk). You should have no problems as long as the resolver used by the mail server you're delivering to handles it properly. To my knowledge, all of them do. A cname is a perfectly reasonable response to a request for a ptr, and should just cause the resolver to restart the lookup with the name specified in the cname response. It results in some extra overhead, but that's a problem any time you use cname records. - -- Stress (N): The condition that occurs when ones mind overrides the body's natural desire to reach out and slap the hell out of someone who desperately deserves it. Joseph C. Lininger, jb...@pcdesk.net -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (MingW32) iQEcBAEBCAAGBQJKoAJHAAoJEMh8jNraUiwqxEcH/AwHnZZ87dhNTfdWqrmdhFyT w5fd+/W7OFnIr/wxDIzJYzWbDltT9NOg6pCIZQ8nDnh9wPfUH0hRDKRvNkvOAi8G HeM4Y3Ig1/ZfEi7BKKI4vZUqhNn3AEQyrJopCjGzC+DyNrUB7qITH0YWqUo0A+NM Wdw124jc+g3EajQ70gVbkBMKOgv0X64tryPqDeE7JQWVyykMXmZjVyYb+BhlBnmG TOcW/f2JBYMSj5c0UxRkMidUO1SURbkLocp6PjdOZtX0/du3gAu0yOlp32Yh9cZS EePAP7gXjr6mui6MrkmY5V0CK01hql15xFUs1M4OOkWQfE9lKQSCKjSKipCRA1Q= =dMA2 -END PGP SIGNATURE- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
