I have 3 sites on Ionos hosts running Joomla 4.4.2, almost up to date. The Global Config page "Send Test Mail" works fine with sendmail or php mail options on two of the sites. The third one, which is the largest, always returns the "could not execute /usr/sbin/sendmail" or similar php mail message. Outwardly, the setup of the 3 sites seems very similar. I compared their configuration.php files, finding only minor differences. The problem system is on a different Ionos server package, as it happens.

I've tried variations of the From email setting and other mail options, no joy. It is not clear to me how Joomla is accessing which system services, or where things are failing. (No detailed message.) Any tips -- before I dig into the SMTP option?


  • Joomla 4.4.2; php 8.1.27; 3 sites on Ionos platforms.
  • Send test Mail works ok on 2 of them. (Sendmail or php)
  • 3rd platform gives "Could not execute: /usr/sbin/sendmail" response.
  • All configuration files identical, nearly.


  • What factors (DNS, email servers, etc.) will produce the error response?
  • How to debug such a failure? (I don't find anything in logs.)

1 Answer 1


Something did change in Joomla's SMTP logic or with my Ionos host account. Finally fixed by using mailer = SMTP option. This requires finding out the host's SMTP server address etc.

Final info used in Global Configuration > Server J4.4.2:

  • From Email: [email protected] (or .org, etc.)
  • From Name: Your Site's name (text)
  • Reply To Email, Name: where to send replies from user
  • Mailer: SMTP
  • SMTP Host: smtp.yourservice (in my case, smtp.ionos.com)
  • SMTP Port: 465 (or as needed by host)
  • SMTP Security: SSL/TLS (or as needed by host)
  • SMTP Authentication: Yes
  • SMTP Username: [email protected] (or .org etc.)
  • SMTP Password: password for above account

I created an SMTP username email account that I called [email protected]. (Substitute your real site address, of course.) The password for that account is the one to use as SMTP Password.

I could not find help or documentation in Joomla or host server space for this setup!

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