Updated FAQ

FAQ.md

@@ -443,14 +443,23 @@ This will "pin" the server certificate to prevent man-in-the-middle attacks.
 Note that older Android versions might not recognize newer certification authorities like Let’s Encrypt causing connections to be considered insecure,
 see also [here](https://developer.android.com/training/articles/security-ssl).
 
+<br />
+
 *Trust anchor for certification path not found*
 
 *... java.security.cert.CertPathValidatorException: Trust anchor for certification path not found ...*
 means that the default Android trust manager was not able to verify the server certificate chain.
 
-You should either fix the server configuration or accept the fingerprint shown below the error message.
+This could be due to the root certificate not being installed on your device
+or because intermediate certificates are missing, for example because the email server didn't send them.
+
+You can fix the first problem by downloading and installing the root certificate from the website of the provider of the certificate.
 
-Note that this problem can be caused by the server not sending all intermediate certificates too.
+The second problem should be fixed by changing the server configuration or by importing the intermediate certificates on your device.
+
+You can pin the certificate too, see above.
+
+<br />
 
 *Empty password*