when i want to send an email with roundcube it takes a while then i get an error "smtp error (-1)"

on the mailserver side theres no trace that roundcube even tried to log in.

on the webserver in the error log :

[16-Feb-2011 23:04:31] Connection timed out (145):

[16-Feb-2011 23:04:31] Failed to connect socket: Connection timed out ():

[16-Feb-2011 23:04:31 +0100]: SMTP Error: SMTP error: Connection failed: Failed to connect socket: Connection timed out in /htdocs/sulat/program/steps/mail/func.inc on line 1479 (POST /?_unlock=loading1297893807322?_task=mail&_action=send)

there no firewall on port 25. normal imap login work just fine.

sending emails using e.g. thunderbird also is fine , just not with roundcube.

anybody could give a hint?

thanks