You got "Error in certificate: Peer's certificate issuer is not recognized." there.
You could send the email using mailx but you need to check the wf mailer and see if it doesn't break the mailer.. In any case, having an incomplete configuration is not good.
Okay basically you will do workflow mailer outbound SSL implementation then.
Check the following blog posts and support note to get the idea.
Using GMAIL's IMAP & SMTP Server Configuring the Oracle Workflow Mailer (Doc ID 2052059.1)
https://ermanarslan.blogspot.com/2014/08/ebs-122-notification-mailer.htmlhttps://ermanarslan.blogspot.com/2015/11/ebs-workflow-mailer-and-gmail.html