[Dovecot] Since Updating Dovecot - Problem by connecting with Client

Hi,

in the last days I've updated my dovecot on my Gentoo System. Before all went fine. Since the update it doesn't work in any way. After the Update my Thunderbird Client says: The Connecction could not proceeded because it was rejected. Another message was, that I should use TLS or SSL to connect. I've not changed my config - probably the update does - and it's only a simple configuration in my home-network.

Has anybody an idea which is causing the problem?

the config looks like this:

protocols = imap imaps listen = [::] default_mail_env = maildir:%h/.mail mechanism = plain

Thx for help

k1x