"lock/disable" user's mailbox

Hello,

not sure if relevant here, but I'm in need of disabling or locking down an user's mailbox, without completely removing the related system account.

It would be nice if said account was not able to receive emails anymore, or "better", until it was re-enabled. Would also be cool if the sender received a warning back, upon the failed dispatch. Does that even make sense? :D

I'm running postfix and dovecot on a debian bookworm VPS. Thanks

-- roughnecks