Ok, for the certificates, you have multiple options here, this is a bit how you want to use it.
You did not mention you os, so i’ll show the debian steps.
If you dont have official certificates, i do suggest you use LetEncrypt Certificates.
If you have other certificates just look what i do here. ;-) and repeat this with your certificates.
I’ll show the debian steps for letsencrypt
apt-get install ca-certificates letsencrypt
letsencrypt certonly --standalone -d mail.example.com
you can add other domainnames for example also, again adjust to your needs.
letsencrypt certonly --standalone -d example.com -d www.example.com -d mail.example.com
The command starts an interactive configuration script which will ask a couple of questions to setup the certificate correctly.
Select Yes to use the default vhost file and specify the settings manually.
Enter the email server’s domain name like mail.example.com.
On the first installation on any specific host, you’ll need to enter a contact email. ( email@example.com )
Next, read the Let’s Encrypt Terms of Service and select Agree to continue.
Then select whether you wish to use both HTTP and HTTPS or to require all traffic
to use encryption by highlighting either the Easy or the Secure option and selecting OK.
If its correct you now have a webserver with https (mail.example.com)
Tip: look at /etc/letsencrypt/options-ssl-apache.conf
You can automatic include these in you apache ssl vhost with. ( if its not already in there. )
IncludeOptional or Include /etc/letsencrypt/options-ssl-apache.conf
IncludeOptional does not make apache complain if the file is missing then its starting
apache, but then it starts without these settings, so use with care.
Configure your postfix to use these certs.
sudo postconf -e 'smtpd_tls_cert_file = /etc/letsencrypt/live/mail.example.com/fullchain.pem'
sudo postconf -e 'smtpd_tls_key_file = /etc/letsencrypt/live/mail.example.com/privkey.pem'
configure postfix to use the TLS encryptions
sudo postconf -e 'smtp_tls_security_level = may'
sudo postconf -e 'smtpd_tls_security_level = may'
sudo postconf -e 'smtp_tls_note_starttls_offer = yes'
sudo postconf -e 'smtpd_tls_loglevel = 1'
sudo postconf -e 'smtpd_tls_received_header = yes'
And we now can restart these services.
systemctl restart postfix apache2
check your logs of its all correct.
Now you kopano outlook client. ! Do note, this might be a bit different from the official doc.
But it works great.
ln -s /etc/letsencrypt/live/mail.example.com/privkey.pem /etc/kopano/ssl/privkey.pem
ln -s /etc/letsencrypt/live/mail.example.com/cert.pem /etc/kopano/ssl/server.pem
I use symlinks here so you van use the default settings from server.conf.
Now for the setting server_ssl_ca_ ( file or path )
For _file, the default can be result for that run :
ln -s /etc/ssl/certs/ca-certificates.crt /etc/kopano/ssl/cacert.pem
Or use for _path
server_ssl_ca_path = /etc/ssl/certs
both should work fine.
Tip: here, if you have your own CA Root. Have a look here:
ln -s /etc/letsencrypt/live/mail.example.com/privkey.pem /etc/kopano/gateway/privkey.pem
ln -s /etc/letsencrypt/live/mail.example.com/cert.pem /etc/kopano/gateway/cert.pem
Since the is a mail setup and you want to protect your mail.
i’ve changed the kopano server.cfg and gateway.conf defaults to :
server_ssl_protocols = !SSLv3 !TLSv1 TLSv1.1
server_ssl_ciphers = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS
server_ssl_prefer_server_ciphers = yes
Now i suggest, start with these requirements for above setup.
Postfix: setup and A PTR and MX record in the dns for mail.example.com
Apache: configure a vhost with the servername mail.example.com ( use this one for your webapp and z-push also )