Sending emails using dovecot auth

Hi All,

I have noticed that dovecot / exim on Cpanels appear to support sending emails via exim after authenticating to Dovecot - see message below

550-Please turn on SMTP Authentication in your mail client, or login to the 550-IMAP/POP3 server before sending your message

We are migrating users mail off cpanels into split mta and dovecot servers and are having problems with some users being abble to send emails afterwards.

Does anyone understand how the CPanel config works?

Thanks

Murray