| George Theall on 2 Aug 2004 14:58:02 -0000 |
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On Sun, Aug 01, 2004 at 03:27:30PM -0400, kaze wrote: > hostedexample.com and www.hostedexample.com both point to a real IP with no > NAT for it setup yet. While it looks like you've fixed the problem (or at least I can get a response when querying for the A record), you may be interested in the following to explain the behaviour you were seeing: Hostnames used as part of the SMTP MAIL FROM and RCPT TO commands are supposed to be "canonicalized", that is, fully-qualified hostnames or literals rather than nicknames or abbreviations (RFC 821, section 3.1). Yet while the RFC says canonicalization must be done, it's silent in how to actually do it and as a result, the methods used vary from one MTA to another, and even across versions of the same MTA. For example, older versions of sendmail look for records of type ANY while 8.12.0 and later look first for A records and then either look for MX records if no A records exist or fails if the DNS server itself fails to answer. Postfix, on the other hand, looks for MX records first; if there are none or the DNS server fails *and* ignore_mx_lookup_error is yes, it looks for A records. Hopefully, this explains why failure to get an A record for your hosted domain from your DNS resulted in mail from some but not all hosts getting through. George -- theall@tifaware.com Attachment:
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