On 08/17/2010 09:33 AM, JD wrote: > Re: a.b.c.d ==> valid.host.name > and valid.host.name ==> a.b.c.d > does not seem to apply to the google smtp server I use for Thunderbird. You did your test entirely backward. You did a forward lookup first, and then checked the PTR of the IP which was returned. There is no requirement for a PTR to match every hostname that resolves to its IP address. Let's finish your test: $ host smtp.gmail.com smtp.gmail.com is an alias for gmail-smtp-msa.l.google.com. gmail-smtp-msa.l.google.com has address 74.125.155.109 The result of this test merely identifies an IP address. Now, let's test to validate that the IP returns a PTR that resolves to the same IP: $ host 74.125.155.109 109.155.125.74.in-addr.arpa domain name pointer px-in-f109.1e100.net. $ host px-in-f109.1e100.net. px-in-f109.1e100.net has address 74.125.155.109 Yep, totally valid. That IP address has a PTR record, and the hostname contained in that PTR resolves back to the same IP address. This host is properly configured. > So, Thunderbird client does not seem to mind that > reverse lookup does not match the name smtp.gmail.com Clients rarely do. It's the servers to which you're going to try to deliver mail that will mind. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
