Horde 'error code 127' problem

[GiorgosI]

Plesk 10.1.1
CentOS 5.5 x64

When we try to send email from Horde we get the error:
There was an error sending your message sendmail returned error code 127

the same time there is the error in /var/log/httpd/error_log:
sh: /sendmail: No such file or directory, referer: http://webmail.xxxxxxxx.tld/imp/compose.php?uniq=1302686268041

I found that the problem is caused due to php safe_mode being On in /etc/php.ini.
If I switch safe_mode to Off, webmail works. The problem is that safe_mode must be On in /etc/php.ini.

Php is running only in CGI mode(server is a container with template 'Pp10 vps optimized' insalled, so php runs only in CGI mode), so I cannot apply php_admin_value in horde's config file.
How can I change safe_mode only for Horde when php is running only in CGI mode?

Thank you

 

[GiorgosI]

I got answer from Plesk support.
I cannot change Horde's or Atmail's safe_mode when php is running in CGI mode.
So, in this case Horde and Atmail get this parameter from global configuration, /etc/php.ini.