Resolve mail configuration Postfix on Centos

At upon time, I want to access mail with php mail, and any error on it (PHP Native and CodeIgniter, so Laravel). So I try many tutorials and I get any keyword since send mail on centos:

Null message body; hope that's ok
postdrop: warning: mail_queue_enter: create file maildrop/71281.94914: Permission denied
postdrop: warning: mail_queue_enter: create file maildrop/71596.94914: Permission denied
postdrop: warning: mail_queue_enter: create file maildrop/72031.94914: Permission denied
postdrop: warning: mail_queue_enter: create file maildrop/72835.94914: Permission denied

the best way to resolve it:

[root@.......]# postfix set-permissions

[root@.......]# mail -s "Hello World" admin@webiot.id

Null message body; hope that's ok
[root@.......]#

All php setting and send mail clear.

probably, this error comes after giving access or chmod.