Disable user login for a few seconds ?

Hi all,

I need to move e-mail files of my users from one file system to another.

I use a MySQL backend on Dovecot 2.1.

How can I do to disable temporary an account while moving files ?

I have an "active" bit in my DB, but if I set it to 0, my MX servers are bouncing mails.

How can I do to disable temporary an account ? In fact, I need dovecot not to do any change on files...

I think I could change account password for a while, and reset it after migration, but it will disturb connected users.

Maybe I could chmod 0 files on my old file system during migration ? How Dovecot will act ?

Thank you :)

Flo