Unable to verify mail notification

I am trying to setup email notifications on manageIQ however I am unable to verify test mail getting error.
I added SMTP server details but no luck,
Can anyone help to setup mail server on manageIQ to send alerts through email

I’ve seen problems where an SMTP server only accepts connections from systems that have a valid reverse-resolvable DNS/IP name, and my MIQ or CFME Appliance only had a temporary name. Otherwise check whether your SMTP server needs credentials and/or TLS to accept connections.

Hope this helps,
pemcg