Email Connection with ssl fails, without ssl works in 5.3.0 and 5.2.1

[apaeffgen]

Espo.ERROR: API [POST]:/:controller/action/:action, Params:Array ( [controller] => EmailAccount [action] => testConnection ) , InputData: {"host":"myserver","port":993,"ssl":true,"username ":"myuser","password":null,"id":"*****"} - cannot connect to host ; error = fsockopen(): unable to connect to ssl://myserver:993 (Unknown error) (errno = 0 ) [] []
[2018-07-07 14:17:51] Espo.ERROR: Display Error: cannot connect to host ; error = fsockopen(): unable to connect to ssl://myserverl:993 (Unknown error) (errno = 0 ), Code: 0 URL: /crm/api/v1/EmailAccount/action/testConnection [] []

This is copied from the log file of espocrm 5.3.0. No more error messages are shown. The ssl-Certificate is a self signed certificate from smeserver9.2 at contribs.org.
Other mail clients, horde and round cube work without any problems.

Any hints how to debug this error further?
Best regards
Andreas

[tanya]

did you install openssl extension on php?

https://stackoverflow.com/questions/21962849/unable-to-find-the-socket-transport-ssl-did-you-forget-to-enable-it-when-you

[apaeffgen]

I upgraded to 5.3.6. The same error occurs. For the OpenSSL - Version / PHP - Version thats used, see below:

OpenSSL support	enabled
OpenSSL Library Version	OpenSSL 1.0.1e-fips 11 Feb 2013
OpenSSL Header Version	OpenSSL 1.0.1e-fips 11 Feb 2013
Openssl default config	/etc/pki/tls/openssl.cnf

openssl.cafile	no value	no value
openssl.capath	no value	no value

This is a copy of the PHP-Info

PHP Version 5.6.36