Lets Encrypt was lately quite often in the media. Letsencrypt is a very easy to use tool which provides certificates for free. Those certificates are valid on most common browsers. I never understood why certificates are expensive that's why I tried out letsencrypt(and I like it!). In this article, I will replace all cacert-certificates on a kolab-server. Therefore I will install the letsencrypt-certificate on: apache2, cyrus-imapd and postfix.
If you have installed Kolab 3.2 on Debian Jessie and if you are using SSL, you might have problems with sieve-filters. If I click on Filters(in webmail), I'll recieve the following error: "Unable to connect to server". /var/log/mail.log shows me:
Sep 18 11:45:35 kolab sieve: STARTTLS failed: localhost [::1]