If you are receiving a message similar to…
Jan 15 22:12:36 ip-10-0-0-133 postfix/postdrop[8301]:warning: mail_queue_enter: create file maildrop/939392.8301: Permission denied
Jan 15 22:12:37 ip-10-0-0-133 postfix/postdrop[8302]:warning: mail_queue_enter: create file maildrop/8821.8302: Permission denied
Jan 15 22:12:37 ip-10-0-0-133 postfix/postdrop[8303]:warning: mail_queue_enter: create file maildrop/14290.8303: Permission denied
You probably have a permission issue with your Postfix installation. This is usually caused by a bad upgrade or maybe user error when moving or recovering mail folders.
This can easily be solved by running the following commands below as root.
/etc/init.d/postfix stop
killall -9 postdrop
chgrp -R postdrop /var/spool/postfix/public
chgrp -R postdrop /var/spool/postfix/maildrop
/usr/sbin/postfix set-permissions
postfix check
/etc/init.d/postfix start
This should work on just about any Linux distro.
