sender callout shorcomings Was: Re: [Exim] sender verify vs.…

At 14:02 -0400 2003/06/27, Greg A. Woods wrote:
[...]
>SMTP was not designed with sender callout attempts in question. If not
>very carefully implemented they cause deadlock situations. Exim's
>sender callout implementation is not careful enough.

could you expand on that please? I also think exim sender callout has
its shorcomings and that, although sender callout can never be
perfect, it could be improved. We might have different ideas on where
it should be improved.

Thanks

Giuliano