Cannot sent message via webmail: “User unknown in virtual alias table”

If Postfix files are corrupted completely, or empty: Create a backup of the current configuration: ~# cp -Rp /var/spool/postfix/plesk /var/spool/postfix/plesk.backup Remove redundant records from the Postfix database: ~# cd /var/spool/postfix/plesk/ ~# for db_file in virtual virtual_domains ; do ls -1 –color=never /var/qmail/mailnames > /tmp/domains.txt hostname -f >> /tmp/domains.txt postmap -s /var/spool/postfix/plesk/$db_file > /tmp/${db_file}_temp grep -f …

Plesk mod_fcgid + php flush() function enable

I set following option in /etc/httpd/conf.d/fcgid.conf file which solves the problem generally (but it would not when Plesk is installed):OutputBufferSize 0 Try to configure OutputBufferSize option for the exact domain, for this create vhost.conf filein domain document root (usually /var/www/vhost/domain.tld/conf folder), add OutputBufferSizeoption with necessary value there and run /usr/local/psa/admin/sbin/websrvmng -a -v