A user reported the following error, which I duplicated with my own mailbox. This is, as before for me, running CentOS 4.1 x86_64, with Interworx 2.1.
There was an error sending your message: sendmail [/usr/lib/sendmail] not executable
That path is specified in at least two files:
/home/interworx/lib/horde/config/conf.php $conf['mailer']['params']['sendmail_path'] = '/usr/lib/sendmail'; /home/interworx/lib/horde/config/conf.xml [/usr/sbin/sendmail]">/usr/lib/sendmail</configstring>
To avoid possible issues with it being specified in other locations, I have simply run the following commands:
ln -s /usr/sbin/sendmail /usr/lib/sendmail chown root:qmail /usr/lib/sendmail chmod 777 /usr/lib/sendmail
These commands setup a link to /usr/sbin/sendmail (which is itself a link), duplicating the permissions and ownership of the latter. This has fixed the issue.