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Re: Question concerning subaddress extension

2005-03-12 16:42:23

I am just trying to implement the subaddress extension in Exim.
What should the subaddress extension do for this example?

   if envelope :detail "from" "foo" {
     redirect "ken(_at_)example(_dot_)edu";

The semantics are well defined for envelope "to".  But envelope
"from"? Obviously, Sieve can not know the separator used by the sender,
if any at all. Yet the above is not forbidden.

IMO the interpreter should do the best it can: Apply the separator
rules it knows.

The alternative of disallowing the test is not particularly palatable.

Another alternative is to require implementations to only extract
subaddresses for domains with known semantics. But that tehn requires
implementations to know when the semantics apply, which may be
an even more difficult problem.

Given that the primary use of subaddress is in conjunction with
envelope "to" (or possibly header "to" or "cc"), it is hard to get
excited about this either way.