We recently starting seeing the following error when sending emails using the Send Email node using SSL:
FailingNodeStackTrace: org.knime.core.node.InvalidSettingsException: Error while communicating with the smtp server: javax.mail.MessagingException: Exception reading response;
nested exception is:
java.net.SocketException: Connection reset
Having raised this with the SMTP provider, they suggested that they had recently moved to TLS 1.2. Is there a way to update the system or the node itself to remain compatible (assuming that Knime is currently only supporting TLS 1.0)?
The error first appeared on Jan 14 however we had upgraded to 4.3 on Dec 12 - this suggests the change is very likely something that took place on the SMTP server. Is there a setting which determines what version of TLS is utilised by the node?
there is no such setting and node uses 1.2 if possible and goes back to 1.0 if not. However this could still be related to moving to TLS 1.2 but the error message doesn’t say much. Have you tried setting log file level to DEBUG and then see if there are more entries in log file regarding Send Email node?
Thank you @ipazin have set log level to debug but it really didn’t reveal anything more about the error itself. As we have successfully used a number of different SMTP providers whilst trying to sort this out (including successfully sending emails with the offending provider using security:NONE and port:26) it again supports the theory that it is the SMTP provider at fault.