Vacation auto-responder; splitting; fetching IMAP

Aloha,

Three things in one, perhaps should have been separate
messages but that seemed spammish and the issues are related.

1. Believe it or not I can't find anything anywhere about
setting up a vacation auto-responder in gnus.  My purpose here
is actually to send an auto-response that I don't read
business email on weekends, for mail sent to said business
address on the weekend.  Okay, with a lot of frustration due
to lack of knowledge, I set up something that sort of mostly
works by using splitting and specifying a function as the
splitting recipe.  However ...

2. If I fetch mail with (effectively) gnus-group-get-new-news,
splitting runs as it should.  But if I fetch mail with
(effectively) gnus-group-get-new-news-this-group, splitting
does not run.  My tracing-gnus-fu is not good enough for me to
as yet have figured out why this may be.  And this matters
because ...

3. When fetching with gnus-group-get-new-news, as noted
splitting runs.  This is all fine if my web browser is not
open to my email service (fastmail in my case).  However, if
the browser is open and there is new mail showing in the
browser, gnus-group-get-new-news won't download it.  However
gnus-group-get-new-news this group (if *Group* is positioned
to INBOX) actually will download this new mail--- but then
splitting won't run.

Can anyone give me any tips here?  Has someone else set up an
autoresponder in gnus?  Can anyone clarifiy 2 and 3, namely
when splitting runs and how -new-news and -new-news-this-group
differ in how they download from an IMAP server?

Mahalo for any thoughts ...

-- 
Bob Newell
Honolulu, Hawai`i

- Via GNU-Linux/Emacs/Gnus/BBDB