On Tue, 6 Apr 2004, Nigel Metheringham wrote:
>
> There are 2 possible uses for recipient callout verification:-
> * Does this recipient exist? - sender is basically irrelevant,
> result can be cached keyed on the recipient only. However this
> requires some knowledge of the recipient site's policies (ie
> will sender=<> work - there are valid cases where it may not)
e.g. dwdm2's secure return path hack, in which visible email addresses (in
my case dot@??? or fanf2@???) are never used as the return path
of a message, so should never receive a bounce. (I use an insecure return
path hack, since I send email from accounts with rarely-published email
addresses.)
> * Can this message (with this sender & recipient) be delivered? -
> sender is very relevant, caching needs to be based on
> sender/recipient tuple.
There's an intermediate stage that is useful for the SRP case,
which is to test the recipient address with a return path of
<postmaster@$qualify_domain>
--
Tony Finch <dot@???>
http://dotat.at/
