🚀 go-pugleaf

In article <1992Apr8.164249.10851@husc3.harvard.edu> utterbac@husc10.harvard.edu (Margot Utterback) writes:
>Recently, I contacted a workstation vendor about the mail system
>that comes with the workstation.  The operating system is based
>on System V release 4.  The mail system failed when the host portion
>of an address was an alias or nickname.  The response was that 
>RFC821 and RFC822 specify that the address must be the official
>domain name and that the entries in the host file and any 
>cname records in the DNS are irrelevent.
>
>This seems a little farfetched to me.  First, the rfcs in theis
>case seem to be irrelevent.  Don't they only specify what would
>be in the headers, not the address given to the mailer?  

Yes, they only specify the format and protocol used between hosts;
mechanisms within a system, or between systems using other protocols, are
not constrained by these RFC's.

However, if the mailer is documented as requiring its input to be a valid
RFC-822 message (perhaps because it simply transmits the message as given,
without reformatting it), then you are not providing valid input.  You'll
have to convince your vendor to change the requirements of the mailer.

>							  Second,
>why limit the address even in the header? You get the host portion,
>ask the DNS what the MX record is.  It will respond with the
>IP address and the canonical name.  Bingo, you have the official
>name, just use that in the rest of the processing.  
>So, do any of you out there see any reason for the limitation?

I believe one of the original reasons for CNAMEs was to ease the migration
from the pre-DNS host names to the DNS host names.  When a machine was
switched to using a DNS name, its old name would be left as a nickname.
The expectation was that many of these nicknames would be temporary.  They
wanted to prevent these transient names from being captured in many
peoples' mail files.  The assumption is that the primary name is likely to
stick around longer.
-- 
Barry Margolin
System Manager, Thinking Machines Corp.

barmar@think.com          {uunet,harvard}!think!barmar