[imp] can't send messages with cvs version

[Andreas Krebs]

hi there,

i'm using the latest cvs (21.11.01) version of horde and imp, almost 
everything works like a charme, but i can' send messages. i get a warning 
'There was an error sending your message'

my apache log shows me the following error message:

[Wed Nov 21 18:00:49 2001] [error] PHP Warning:  Undefined index: 
prepend_header in /usr/local/apache/htdocs/horde/imp/lib/IMP.php on line 866

the mta log doesn't even show a connection.

versions are:

Horde: 3.0-cvs
IMP: 4.0-cvs
Turba: 2.0-cvs
Gollem: 0.0.1-cvs
Nic: 0.0.2-cvs
Kronolith: 0.0.3-cvs
Jonah: 0.0.3-cvs
Troll: 0.0.2-cvs
Chora: 0.6.5-cvs
Whups: 0.0.1-cvs
Nag: 0.0.2-cvs

Php 4.0.6 with PEAR from CVS

any suggestions would be welcome
thanks

Andreas