Removing sharing of mailbox when granted user is deleted

[Paolo Cravero]

Hi.
I've searched with "ACL" keyword all my cyrus-info archive and nothing similar
came up in the last 18 months.

The situation is:
- user A shares a mailbox with user B
- user B at some point is deleted

how do I remove the ACL on A's folder for B?

The only way I can think of is a dump of mailboxes.db, grep for B account and
then further removal of the stale ACL. Is there another way to do it?

I know it (probably?) doesn't hurt to keep the broken ACL, but a re-creation of
an account called B would automatically(?) grant access to that folder, wouldn't it?

TIA,
Paolo