Overquota flag and auth caching

[list at ptld.com]

> On 09-13-2022 5:17 am, Christian Rößner wrote:
> 
> The result is that mails are still accepted, even a user went over quota resulting in bounces.
> What is the correct way to use the over quota flag and which solutions can be taken to invalidate the user?
> Is it possible to do this in a Lua user  backend? Any other method?


It is unclear in your message if you are aware of how you can use have your MTA check quota during delivery, and reject before accepting, to prevent back-scatter. For example if you are using Postfix you can use the policy service to do this in main.cf:

     smtpd_recipient_restrictions =
         ...
         check_policy_service unix:private/quota-status

And here are the docs on setting up quota for postfix on the dovecot side:

     https://doc.dovecot.org/configuration_manual/quota_plugin/#quota-service