An email sent to several recipients is not delivered, returning one of these error messages in
554 mail server permanently rejected message (#5.3.0) 451 4.7.1 Service unavailable - try again later 451: qq trouble in home directory (#4.3.0) 4.5.1 Mailbox full
The error occurred because the mailbox of at least one of the recipients is full. This behavior was implemented to help control spam messages.
You can disable this behavior with the help of the following commands:
MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -u admin psa -e "REPLACE INTO misc VALUES ('reject_mail_when_overquota', 'false')" /usr/lib64/plesk-9.0/mail_mailbox_restore --handlers-only