fatal: read /etc/postfix/: Is a directory

Jun 20 09:35:27 mail postfix/master[19495]: warning: process /usr/lib/postfix/sbin/smtpd pid 19508 exit status 1
Jun 20 09:35:27 mail postfix/master[19495]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling
Jun 20 09:36:19 mail postfix/cleanup[19562]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:36:20 mail postfix/master[19495]: warning: process /usr/lib/postfix/sbin/cleanup pid 19562 exit status 1
Jun 20 09:36:20 mail postfix/master[19495]: warning: /usr/lib/postfix/sbin/cleanup: bad command startup -- throttling
Jun 20 09:36:27 mail postfix/submission/smtpd[19573]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:36:28 mail postfix/master[19495]: warning: process /usr/lib/postfix/sbin/smtpd pid 19573 exit status 1
Jun 20 09:36:28 mail postfix/master[19495]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling
Jun 20 09:36:59 mail postfix/master[19495]: warning: unix_trigger_event: read timeout for service public/pickup
Jun 20 09:37:20 mail postfix/cleanup[19931]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:37:21 mail postfix/master[19495]: warning: process /usr/lib/postfix/sbin/cleanup pid 19931 exit status 1
Jun 20 09:37:21 mail postfix/master[19495]: warning: /usr/lib/postfix/sbin/cleanup: bad command startup -- throttling
Jun 20 09:37:28 mail postfix/submission/smtpd[19938]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:37:29 mail postfix/master[19495]: warning: process /usr/lib/postfix/sbin/smtpd pid 19938 exit status 1
Jun 20 09:37:29 mail postfix/master[19495]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling
Jun 20 09:37:59 mail postfix/master[19495]: warning: unix_trigger_event: read timeout for service public/pickup
Jun 20 09:38:17 mail postfix/postfix-script[19952]: stopping the Postfix mail system
Jun 20 09:38:17 mail postfix/master[19495]: terminating on signal 15
Jun 20 09:38:17 mail postfix/postfix-script[20116]: starting the Postfix mail system
Jun 20 09:38:17 mail postfix/master[20118]: daemon started -- version 3.3.0, configuration /etc/postfix
Jun 20 09:38:17 mail postfix/cleanup[20122]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:38:18 mail postfix/master[20118]: warning: process /usr/lib/postfix/sbin/cleanup pid 20122 exit status 1
Jun 20 09:38:18 mail postfix/master[20118]: warning: /usr/lib/postfix/sbin/cleanup: bad command startup -- throttling
Jun 20 09:38:43 mail postfix/submission/smtpd[20484]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:38:44 mail postfix/master[20118]: warning: process /usr/lib/postfix/sbin/smtpd pid 20484 exit status 1
Jun 20 09:38:44 mail postfix/master[20118]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling
Jun 20 09:39:18 mail postfix/cleanup[20554]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:39:19 mail postfix/master[20118]: warning: process /usr/lib/postfix/sbin/cleanup pid 20554 exit status 1
Jun 20 09:39:19 mail postfix/master[20118]: warning: /usr/lib/postfix/sbin/cleanup: bad command startup -- throttling
Jun 20 09:39:44 mail postfix/submission/smtpd[20562]: fatal: read /etc/postfix/: Is a directory
Jun 20 09:39:45 mail postfix/master[20118]: warning: process /usr/lib/postfix/sbin/smtpd pid 20562 exit status 1
Jun 20 09:39:45 mail postfix/master[20118]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling