This is an RTFM, but I reproduce the relevant section of filter.txt
anyway:
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9. Significant deliveries
When in the course of delivery a message is processed by a filter file,
what happens next, that is, after the whole filter file has been
processed, depends on whether the filter has set up any significant
deliveries or not. If there is at least one significant delivery,then
the filter is considered to have handled the entire delivery
arrangements for the current address, and no further processing of the
address takes place. If, however, no significant deliveries have been
set up, Exim continues processing the current address as if there were
no filter file, and typically sets up a delivery of a copy of the
message into a local mailbox. In particular, this happens in the
special case of a filter file containing only comments.
The delivery commands deliver, save, and pipe are by default
significant. However, if such a command is preceded by the word
"unseen", then its delivery is not considered to be significant. In
contrast, other commands such as "mail" and "vacation" do not count as
significant deliveries unless preceded by the word "seen".
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On Thu, 14 Oct 1999, Drew Berendts wrote:
> In the course of writing a system-wide filter, I have seen several
> references in the Exim documentation to the commands "seen" and "unseen" as
> relates to string expansion. I have spent a fair bit of time reviewing the
> Exim WWW site and related documentation, but cannot find a clear, simple
> explanation of these commands and what they indicate in regards to string
> expansion.
>
> Any simple explanation of these terms would be VERY appreciated.
>
> Thank you.
>
> Drew Berendts
> Internet Security Engineer
> Verio, Inc.
>
>
>
> --
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim details at http://www.exim.org/ ##
>
