I have Owncloud installed on the same Domain as a CMS software that uses mails all the time.
In the CMS sending mails works but when I use the same settings (double checked them 200 times) I get the following error message:
A problem occurred while sending the email. Please revise your settings. (Error: Connection could not be established with host dedivirt374.your-server.de :stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:1408F10B:SSL routines:ssl3_get_record:wrong version number)
OwnCloud Community: 10.3.2.2
Server SSL: Let’s encrypt via Hetzner Manager Server which seems to be working perfectly since all my domains are secured with it and never fail to send/recieve mails.
Let me know if you need more information in order to give some advice on where to start looking for a solution.