IPv6 isn't SMTP

Dave Crocker dhc2 at dcrocker.net
Fri Mar 28 01:46:58 UTC 2014

On 3/27/2014 6:51 AM, Blake Hudson wrote:
> The primary issues I see with SMTP as a protocol related to the lack of
> authentication and authorization. Take, for instance, the fact that the
> SMTP protocol requires a mail from: and rcpt to: address (more or less
> for authentication and authorization purposes),

Actually, for neither.

Mail from was mislabeled; it merely provides an address to send return 
notices to, which is why it makes sense to permit it to be different 
from the rfc5322.From value.  And, of course, rcpt to specifies a 
recipient address.

auth/auth functions were tacked on much, much later, which is why their 
utility is so constrained. (20 years?)

> but then in the message
> allows the sender to specify a completely different set of sender and
> recipient information that gets displayed in the mail client.

Yeah.  Almost like it is approximating the difference between what is on 
the outside of a postal envelope versus what is on the letterhead and 
opening of a piece of paper mail, which also permit such independence...

The essential problem with seeing these as 'problems' is confusing 
'common' with 'required'.  Common scenarios are fine, but so are the 
variants.  The variants often blow apart the simplifying assumption that 
one can incorrectly believe from the common scenarios.

Dave Crocker
Brandenburg InternetWorking

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