[imp] error during send message

[Ilya]

in latest cvs of everything (5min) as well as 1 day ago, whenever i try to send
a message i get:
Fatal error: Call to undefined function: send() in
/usr/local/www/horde/imp/lib/Compose.php on line 116

using smtp mailer and host set to localhost


using sendmail works fine, but i'd prefer not to use due to header settings of
return-path

any suggestions?
IMP Version
IMP: 4.0-cvs 
Other Horde Applications
ingo: Yes (Version: 2.0-cvs) 
turba: Yes (Version: 2.0-cvs) 
PHP Version
View phpinfo() screen 
View loaded extensions 
PHP Version: 4.3.3RC1 
PHP Major Version: 4.3 
PHP Minor Version: 3 
PHP Version Classification: dev 
You are running a supported version of PHP. 
PHP Module Capabilities
IMAP Support: Yes 


PEAR
PEAR Search Path (PHP's include_path):  /usr/local/share/pear:. 
PEAR: Yes 
Recent PEAR: Yes 
Mail_RFC822: Yes 
Mail_Mime: Yes 
Log: Yes 
DB: Yes 
Net_Socket: Yes 
Date_Calc: Yes 
Auth_SASL: Yes 
Net_URL: Yes 
HTTP_Request: Yes 
File_CSV: Yes