This article refers to a (test) certificate but none has been attached. To be fixed.
The pre-installed email certificates can be viewed at "Settings > Certificates > Email certificates". It is possible to add more certificates using the command line (as the UI support for adding them is missing).
In this help article, we use the certificate by the name "JSCCinternalCA.crt" as an example. Replace it with the certificate you want to add.
For executing the commands below you will need the Developer mode.
1. Copy the certificate file (*.crt) from PC to the Home folder "
$HOME" of your Sailfish OS device, first. Use the method of your preference as suggested in this help article.
2. In your Sailfish device, get the super-user rights (SSH password) first (see the Developer mode article, if needed). Copy the certificate further to folder "
devel-su ## you will need your SSH password here
cp $MYHOME/JSCCinternalCA.crt /etc/pki/ca-trust/source/anchors
3. Run the command update-ca-trust
4. Open the menu page "Settings > Certificates > Email certificates". Check that the added certificate "JCSS internal CA" can be found in the list.
Select that certificate. Restart your device.
5. Turn Developer mode off if you do not need it anymore.