File: //usr/share/webmin/virtual-server/help/template_spam_exitcode.html
<header>When an over-quote user receives email</header>
This option controls what happens when a mailbox that is close to or over its
disk quota receives email that would put it over quota. By default Virtualmin
will bounce the email back to the sender - but if you select the <b>Queue</b>
option, email will be held in the local mail queue and re-tried at regular
intervals. <p>
If the user's disk usage eventually drops below quota, the message will be
delivered. However, if usage never drops the message will be bounced back to
the sender after a period configured by the mail server (typically 5 days). <p>
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