[Alerting] email action fails with no useful error message

[pmuellr]

Kibana version: 7.7 build candidate

Elasticsearch version: "

Describe the bug:

Email action fails to run, reporting a failure in the Kibana.log, but not what the failure was.

As seen in logs:

2020-04-02T15:06:16Z [debug][taskManager]: Running task actions:.email 7ee7...
2020-04-02T15:06:16Z [error][taskManager]: Task actions:.email 7ee7... failed: Error: error sending email

Any additional context:

Customer thinks this is probably a configuration error on their smtp proxy.

I'm thinking there should have been a message from the actions plugin here, so a little concerned there wasn't. Should try to repro an error scenario like this and do a little debugging.

Even if the actions plugin did generate an error log message, not completely clear what it would write, since it would presumably have to trust that the error message from nodemailer was "safe" enough to write to the Kibana logs.

May also be a case where the event log would be a useful place to dump these 3rd party service error messages.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[pmuellr]

This should have been resolved by #79474 - my bad for not referencing it there.

But, good excuse to do a manual check that we are actually doing that. Assuming it works as intended, we can close this.

[ymao1]

Confirmed that this was resolved by #79474