David Woodhouse wrote:
Please explain why you think that it is ridiculous. You have caused a
situation in which I may not forward your mail but I offer you the
forwarding address to use for yourself... why is it unreasonable to
expect you to _use_ the address you're offered?
Because, I sent the message to bob(_at_)acme(_dot_)com for delivery. If Bob wants
that message forwarded without me knowing it, the forwarder choose to do
that. If I don't want the forwarder to use my domain in the return path
of the mail they generate, Bob can choose to respect that. However, if
I get a 551 that bob should be contacted on another address:
(1) the sending user may reevaluate how or to whom to send that message.
(2) there may be policies in place to prevent my MTA from speaking
directly to the new destination. And while that too may generate a 55x
error, the resulting error to the user will be even more confusing.
(3) specifically for automated services that use it is legitimate to
require Bob to subscribe with an email address accepts mail directly.
The service, with that error message, can intruct Bob to provide an
email address on a system that will respect that services wishes
published through SPF.
I am not arguing that reattempting with the new email address provided
in the 551 is not a good idea, but rather there are many legitimate
reasons why a bounce message should be generated to the sending
human/automation and thus mandating it is ridiculous.
--
// Theo Schlossnagle
// Principal Engineer -- http://www.omniti.com/~jesus/
// Postal Engine -- http://www.postalengine.com/
// Ecelerity: fastest MTA on Earth