Jacob,
The DSN standards (RFC 1891, 1892, 1894) have now been
ready for more than two years. Yet very few mailers support
them. What can be done to get more support?
I'm afraid there are two major obstacles to the widespread use of DSN:
1. the amount of User Agents supporting DSN is low
2. from my experience I know that in a significant number of cases
the problem why DSN is not supported by a company e-mail infrastructure
the firewall that's being used in the real world. In many cases the
firewall has an active mail component, thus limiting the support for
SMTP and extensions to what the firewall provides. And more often then
not the firewall does not support DSN or does not even ESMTP at all!
Does sendmail produce DSN in the standardized format? If
yes, how can we get people to update to a more recent
version of sendmail. If not, how can we get it to support
I think Sendmail is not the problem. Due to Sendmail's security
problems, most customers have recent releases of Sendmail deployed.
Mail clients can support DSNs in several ways. I list them
below in my suggested priority order:
(1) Display standardised DSNs in a standard format, which
contains the information the user needs in easy to read
format.
(2) Allow filtering incoming DSNs to a special folder.
(3) A command to look at a sent message, and then get a
list of all delivery and receipt notifications for this
message, one line per note. Something like this:
Received by: xxx
Received by: (printed on paper) yyy
Delivered to: zzz
Could not be delivered to: qqq
This option is of course very useful in conjunction
with option (2).
(4) Commands to request delivery and receipt notifications
and to request supression of them.
Mail clients cannot be expected to support this until
sendmail and other MTA software starts supporting them.
Yes, but I think in many cases the vendors of UA software should do more
to support DSN's and vendors of firewalls should get up to date with
their e-mail software.
Regards,
/rolf
Rolf E. Sonneveld
Sonnection
The Netherlands