Re: Gnus Questions #1: Article Expiry

[Lars Magne Ingebrigtsen <larsi@gnus.org>]

Dave Abrahams <dave@boostpro.com> writes:

> * What's the difference between marking an article "expirable (E)" and
>   `marking it expired' as described by [[info:gnus#Spam and Ham
>   Processors]]?

I'm not that familiar with the spam processing thing, so I'm not sure.
I mean, there is no mark for "expired articles" (i.e. deleted articles)
as far as I know.  Just "expirable articles".

> * [[info:gnus#Expiring Mail]] and [[info:gnus#Group Parameters]] both
>   mention articles being `put through the expiry process,' but that
>   process is never spelled out.  What exactly is involved?

It's what's described on the "Expiring Mail" node?

> * I presume that "expiring" an article means the same as "putting the
>   article through the expiry process" (?)

Yes.

> * What's the difference between `gnus-summary-expire-articles' and
>   `gnus-summary-expire-articles-now'?  The documentation doesn't make
>   that clear.

The latter says:

"This means that *all* articles that are marked as expirable will be
deleted forever, right now."

> * What's the point of backend-specific expiry settings like
>   nnfolder-inhibit-expiry (I'm referring to the `nnfolder-' part when I
>   say `backend-specific')?  Don't we have enough other ways to say "this
>   group/server isn't expirable?"

It's sometimes more convenient to inhibit it on a server basis than on a
Gnus group basis.

> * [[info:gnus#Expiring Mail]] mentions `having auto expiry switched on'
>   but doesn't say how to do that.  Are we talking about the auto-expire
>   group parameter here, or something else?

That, and `gnus-auto-expirable-newsgroups'.  See the index entry for
`auto-expire'. 

> * "Total Expire" and "Auto Expire"
>
>   * The main point of using "Total Expire" instead of "Auto Expire"
>     seems to be that with "total expire" you can keep a distinction
>     between expirable (`E') and other marks that indicate an article was
>     read... until expiry actually runs.  At that point, if you're using
>     total expire they're all treated the same.  With "auto expire," on
>     the other hand, you know that only articles marked `E' will be
>     put through the expiry process.

Well, sort of.  With total expire, you expire all old articles.  If you
don't use total expire, the expiration process will only consider
"E"-marked articles.

You can "E"-mark them manually, or you can switch on auto-expire and
have Gnus set the "E" mark automatically.

>   * From [[info:gnus#Adaptive Scoring]] I think I conclude that adaptive
>     scoring takes effect at expiry time, and "auto-expire" changes all
>     read marks to `E' too early for adaptive scoring to do its work.  Is
>     that right?

No.  If you set the "E" mark on all articles (whether automatically or
manually), Adaptive Scoring won't be able to tell whether you're read an
article or not, so it can't do its thing.

>   * [[info:gnus#Expiring Mail]] seems to contradict my understanding,
>     though: it claims that "auto-expire" gives me "more marks to work
>     with."
>
>     ,----
>     | Another advantage of auto-expire is that you get more marks to work
>     | with: for the articles that are supposed to stick around, you can
>     | still choose between tick and dormant and read marks.  But with
>     | total-expire, you only have dormant and ticked to choose from
>     `----
>
>     Okay, now that I read it again I think it's saying that with
>     "auto-expire," if I can somehow produce a mark other than `E' for an
>     article that's been read,, that article can persist even if it's
>     neither dormant or ticked.  That's fine as far as it goes but
>     mentioning it seems almost pointless, since Gnus is going to
>     automatically mark everything I read as `E'.  What am I missing?

Is it talking about adaptive scoring there?

>   * This (from [[info:gnus#Expiring Mail]]) seems confusing for what I
>     think are related reasons:
>
>      ,----
>      | Note that making a group auto-expirable doesn't mean that all read
>      | articles are expired--only the articles marked as expirable will be
>      | expired
>      `----
>
>     If auto-expire automatically marks articles expirable when you read
>     them, doesn't that /necessarily/ mean all read articles are expired
>     (except articles you read in the past?).

No.  You can remove the "E" mark manually.

>     Is there a common usage
>     model where people set auto-expire and then use some explicit
>     commands to change the read mark on some of their articles after
>     Gnus has already marked them `E'?

Yes.  I used to do that back before SpamAssassin.  I used auto-expire to
"E" mark everything (which was mostly spam), and then I manually "d"'d
the non-spam message.

>   * Aren't there a bajillion other ways to do the following, including
>     by customizing the "auto-expire" group parameter?  Why would I do it
>     as below (see [[info:gnus#Expiring Mail]]) instead?
>
>     ,----
>     | To avoid having articles marked as read marked as
>     | expirable automatically, you can put something like the following in
>     | your `~/.gnus.el' file:
>     | 
>     |      (remove-hook 'gnus-mark-article-hook
>     |                   'gnus-summary-mark-read-and-unread-as-read)
>     |      (add-hook 'gnus-mark-article-hook 'gnus-summary-mark-unread-as-read)
>     | 
>     `----

Yes, that seems rather excessive.

> * How does the expire-age group parameter come into play?
>   - Does it prevent me from marking articles as expirable for a period?
>   - Does it prevent auto-expire from marking articles expirable?
>   - Does it simply exempt articles that are too young from expiry?

The latter.

> * Suggestion: Rename `gnus-auto-expirable-newsgroups'
>   `gnus-auto-expirable-groups' since, generally, auto-expire only
>   applies to mail and not to nntp.

Gnus has historically used "newsgroups" and "groups" as synonyms, and I
think that boat has sailed a long time ago.

> * As far as I can tell, the user experience of Agent expiry is
>   completely different from that of regular article expiry.

Yes.  :-)

>   This isn't
>   explained anywhere, but IIUC from experiments, agent expiry doesn't
>   delete any mail except from the agent's cache.  Instead it merely
>   flushes (some part of) the agent's cache.  Is that right?

Yes.

>   I and several of my friends have long been plagued by the symptom that
>   if I delete an IMAP message in some other mail client, it still hangs
>   around in Gnus.  I've beat my head against
>   `gnus-agent-regenerate[-group]' and `gnus-agent-flush-*' and other
>   trix for years trying to correct it, but never found a reliable
>   formula.  Agent expiry seems to be the key.  I think.  Have I got that
>   right?

There have been many reports about nnimap and the Agent not playing nice
with each other.  I have yet to delve into that morass.  But I will.  :-)

-- 
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  bloggy blog http://lars.ingebrigtsen.no/