failure to send on some accounts

Hello,

I'm getting an error on sending from newly setup accounts. I have 1
account which sends fine, but adding users subsequently (via my
webhosts mail user page), gives the following error:

[05-Dec-2006 09:14:15 -0800] SMTP Error: SMTP error: Authentication
failure: Invalid response code received from server in /home/.leona/btt/bttlongbeach.com/webmail/program/steps/mail/ sendmail.inc on line 253

I recently moved the directory that the roundcube software resides,
however I'm not sure why one account works and others don't. Testing
the other accounts via my webhosts default webmail application works
for all accounts.

any suggestions would be greatly appreciated. thanks! -lev