Selinux Allow Sendmail

check default value httpd sendmail

#/usr/sbin/getsebool -a | grep httpd_can_sendmail

if you want show all httpd

/usr/sbin/getsebool -a | grep httpd
see below  if  it's off let change to on


httpd_can_sendmail --> off

#setsebool -P httpd_can_sendmail on 

or

 #setsebool -P httpd_can_sendmail 1

if you want  allowed to make a connection over the network  let change
httpd_can_network_connect --> off   to  on

credit  CentOS selinux Booleans