smtp without ssl not working

[techlov3r]

Hi,

somehow I can't get the e-mail notification to work without ssl in Wallos v2.44.0.
Although it is set to "None" in the settings, I always get the following error message when testing:

SMTP Error: Could not connect to SMTP host. Connection failed. stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages: error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed

I can't find anything relevant in my webserver logs either.
Does anyone have any tips as to what could be going on here, or whether this is a bug?

Best regards,
Daniel