[webmin-l] Failed to save mail file options : Missing or invalid UIDL format

[<da...@da...>]

Hello Jamie and users, I have been trying to configure and deploy a Java based web-mail client. I am having some issues with this client. Before I get flamed on the web-mail clients ML I need to make sure the Dovecot IMAP server is running correctly. The Dovecot IMAP server is up-and-running (netstat -a) but I noticed in the Dovecot webmin module: Dovecot IMAP/POP3 Server ==> Mail Files some fields and checkboxes for:

Mail file location 	 Detect automatically
                         Inbox and folders in ~/Maildir

Index files location 	 Default (in Maildir directory)
                         Other directory

Control files location 	 Default (in Maildir directory)
                         Other directory
..

UIDL format              Not set (WARNING - Dove may not start)

Changing or leaving the defaults give the same error condition: Failed to save mail file options : Missing or invalid UIDL format

For some years now I have used only /Maildir. I don't know what UIDL is and Googling this term did not reveal much. If anybody has a howto, resource or link to navigate please advise, David.