Could not execute: /usr/sbin/sendmail
In Wordpress, it refuses to send email. Once such instance is the Forget password window and you see the message
The e-mail could not be sent.
Possible reason: your host may have disabled the mail() function.
This is ONE possibly most common situation.On most Development servers, the SELinux is probable turned OFF or in permissive mode. However on the Production servers, they are almost always set to ON. In the web server document directory, check if the following SELinux status;
$ getsebool httpd_can_sendmail
It should be in status OFF. Change the status to ON and restart Apache with the command
$ setsebool -P httpd_can_sendmail on
$ systemctl restart httpd.service
Second common situationStill not receiving emails from apache or Wordpress? It is possible Postfix SMTP server is using values that the email relay SMTP is not accepting. Check the maillog for any errors such as this;
said: 450 4.1.8 <email@example.com>: Sender address rejected: Domain not found (in reply to RCPT TO command))
sendmail: NOQUEUE: SYSERR(apache): /etc/mail/sendmail.cf: line 0: cannot open: Permission denied
This is a story for another time.