Problem with web based reply

I have just installed rt ver 1.0.6 onto a debian system with sendmail ver

the autoreply to a message to the mail gateway works fine.
when I try to send a reply via the web interface I get an internal server
error message.
checking the apache logs shows the following:

Could not send mail :frowning:

Tried to launch this command: /usr/lib/sendmail -oi -t
[date time] [error] [client] Premature end of script headers:

Anyone have any thoughts on this ???

I am using what I believe to be the latest version packaged for Debian…