Hi,

If you're having problems with SugarCRM email on Debian (and almost certainly on Ubuntu too), check that the memory allocated to the CLI environment for PHP is increased, the CLI environment and the Apache environments are quite different.

/etc/php5/cli/conf.d/php.ini

The symptoms I was seeing were that my mailbox was being accessed, mail was being marked as read, but no mail was actually appearing in the mailbox in SugarCRM,

Hope this helps someone...