==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.8 MYSQL edition
- Deployed with iRedMail Easy or the downloadable installer? yes
- Linux/BSD distribution name and version: Ubuntu 18.04.1
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): NGinx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

We wan't use the existing MySQL DB (vmail/mailbox/username) to verify e-mail addresses with an external web-application. This data transfer will be only encrypted. I have enabled SSL in the MySQL configuration.

- cert files in /etc/letsencrypt/live/<domain>/*.pem (other locations eg. /etc/mysql/ same problem)
- ssl config in /etc/mysql/mysql.conf.d/mysqld.cnf enabled with

ssl=1
ssl-key=/etc/letsencrypt/live/<domain>/privkey.pem
ssl-cert=/etc/letsencrypt/live/<domain>/cert.pem
ssl-ca=/etc/letsencrypt/live/<domain>/fullchain.pem

-  "sudo -u mysql cat /etc/letsencrypt/live/<domain>/fullchain.pem" can read this file

I get this error in mysql error log:

[Warning] Failed to set up SSL because of the following SSL library error: SSL_CTX_set_default_verify_paths failed

and

mysql> SHOW GLOBAL VARIABLES LIKE '%ssl%';
...
| have_openssl  | DISABLED |
| have_ssl      | DISABLED |
...