[imp] invalid response

[Christian Bartels]

hi,

i'm using horde 3.0 and imp 4.0. it worked great 2 weeks but suddenly i cannot 
send mails to recpients of other servers anymore. i cannot think of any 
changes of the server which could cause this. the exact error message ist 
this:

Jan 14 08:04:25 HORDE3 [error] [imp] unable to add recipient [cb2206 at web.de]: 
Invalid response code received from server [on line 904 of 
"/var/www/www.genux.de/htdocs/horde3/apps/imp/compose.php"]

i do not have any problems sending mail with several client applications like 
kmail, outlook, etc.
does anyone have a clue what could be wrong or how i could get more 
information about this?

thx a lot!

best regards
christian