Howto use certificates from letsencrypt.org with cyrus

[Thomas Luft]

Hi everybody,

at http://letsencrypt.org one can get free and valid SSL certificates. 
After registration of the server I have three files: privkey.pem, 
cert.pem and chainfile.pem

When I try to use these files in /etc/imapd.conf I see that TLS can not 
be started:

Dec 10 13:52:15 kolab imaps[19580]: unable to get certificate from 
'/etc/letsencrypt/live/domain.com/cert.pem'

My imapd.conf looks like this:
tls_server_cert:    /etc/letsencrypt/live/domain.com/cert.pem
tls_server_key:     /etc/letsencrypt/live/domain.com/privkey.pem
tls_server_ca_file: /etc/letsencrypt/live/domain.com/chain.pem

I tried to copy the cert.pem and chown it to cyrus, but this did not 
help. Does cyrus need a specific format of the cert/key/chain file?

Kind regards

Thomas