The error message is as follows:
"### An error occurred while trying to send an email! (triggered a few seconds ago)
The Graylog server encountered an error while trying to send an email. This is the detailed error message: org.apache.commons.mail.EmailException: Sending the email to the following server failed : imap.fleuchaus.com:587 (javax.mail.MessagingException: Could not convert socket to TLS; nested exception is: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target)"
Any ideas on how I might solve this?