[exim-dev] Re: Running .forward files at verification time

Tony Finch writes ("Running .forward files at verification time"):
> (2) As a counterpart to the forbid_filter_all option, we need an
> ignore_forbidden_expansions option, which means that forbidden expansions
> do not cause an error at verification time; instead Exim should just give
> the .forward file the benefit of the doubt. Would it be sufficient to just
> make them expand to the empty string?

A better alternative would be to abandon the filter file processing
and claim to have `delivered', ie do the same as `seen finish'.

Otherwise messages that would be accepted by the filter when they are
seen could be rejected, and there would be no way to code the filter
correctly to avoid this.

An explicit test for `we are verifying' would be useful too (I haven't
checked the filter spec to see if that already exists).

> (3) A redirect router which has verify_only and check_local_user is a
> configuration error at the moment - it cannot work, because Exim cannot
> switch to the local user at verification time to run the router. I suggest
> that in this situation, Exim should omit the switch-to-user effects of
> check_local_user, and probably also automatically turn on
> forbid_filter_all and ignore_forbidden_expansions.

That sounds like a good idea. Turning on the safety checks is
essential I think.

Ian.