Expiry puzzle

[Brendan Halpin]

I'm trying to archive about 4 years worth of mail[1], using expiry with an
expiry-target of nnml:group-archive.YYYY where YYYY is the year. 

I've adapted an example from the manual for the relevant
expiry-wait-function: 

(setq nnmail-expiry-wait-function
      (lambda (newsgroup)
        (cond ((string-match "normal-mail" newsgroup) 365)
              ((string-match "gmail" newsgroup) 365)
              ((string-match "important" newsgroup) 'never)
              (t 7))))

Initially this worked unproblematically, but it is extremely slow (about
2 sec per message, and tens of thousands of messages). So I interrupted
it with C-g, and restarted it later. The first few times I did this, it
continued to expire messages. However, some older mail messages seem to
get left behind, and finally the process ceases to expire messages. That
is, on leaving the group I get "Expiring articles...done" but nothing is
expired.

Obviously, something is inconsistent. Where should I look?

Regards,

Brendan

[1] It is a tribute to gnus' design that a single folder of accumulated
mail is only starting to get unwieldy after more than four years.
-- 
Brendan Halpin,  Department of Sociology,  University of Limerick,  Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F1-009 x 3147
mailto:brendan.halpin@ul.ie  http://www.ul.ie/sociology/brendan.halpin.html