Sending mail failed

[nomoo]

Hello.

Roundcube 0.3.1

Client's browser: ff 3.5.7

Sometimes when one of the users tries to send a message nothing happens, after a long-long loading 'page not found' appears.

In logs:
[29-Jan-2010 14:26:02] Invalid response code received from server (-1):
[29-Jan-2010 14:26:02] Invalid response code received from server (-1):
[29-Jan-2010 14:26:02 +0000]: SMTP Error: SMTP error: Failed to send data in /usr/local/www/roundcube/program/steps/mail/func.inc on line 1365 (POST /cube/?_task=mail&_action=send)

I'm using SSL for imap and smtp connetions.

Thanks in advance.

[SKaero]

Enable the debug_logger plugin and post the imap log.