[Dovecot] temporary disable account

[Lampa]

Hello,

is there some way how to disable temporarily account or access to
files. I need to backup with tar, but there is problem when tar is
reading and some file changed (with --ignore-failed-read it continues
but archive is not created and without --ignore-failed-read it fails).
Some accounts are huge ;( Need something like qmail sticky bit or
world writable directory - qmail is not delivering when one of above
conditions hits.

Thank you for helping me.
-- 
Lampa