Prohibit dots in folder names

Hello Dovecot Community,

I am using Dovecot 2.2.13-12~deb8u1 (Debian Jessie).

separator = / listescape plugin is NOT active LAYOUT=fs is NOT active

I would like to prohibit a creation of folders with dot "." in the names

so creation of a folder "foo.bar" should NOT be possible. Currently, when I create "foo.bar" in Outlook 2013 it will be created but won't be synchronised with the mail server - Outlook shows it as "foo.bar (Only this computer)". Ideally the user should receive an error message informing that "the folder foo.bar could not be created."

Thank you for your help.

Regards, Marek Grondecki