Received Message:appears to be an invalid or non-working recipient email address

Verified address valid, recipient receives emails with the exception of this condition.  This occurred with two separate emails.
 

1) we always need your club number in every post
2) What email address are you referring to?

So sorry for omitting club number: 2383This email address is being protected from spambots. You need JavaScript enabled to view it. appears to be an invalid or non-working recipient email address. (No advertised SMTP servers are accepting mail.)hughesm@juniper.net appears to be an invalid or non-working recipient email address. (No advertised SMTP servers are accepting mail.)
And got this message when I emailed out our Meeting Agenda:
Emails to the the following members were skipped for the reasons listed below:
Sai Ankala (invalid/non-working email address)All these statements were verified as incorrect by our webmaster.  All emails are valid.

I'm new to your site, so I apologize for any incorrect conduct.

I was able to send test emails to all 3 using the basic email tool in your members list.

I saw no failures.

I was able to send test emails as well. Why would I see failures? Was it just a glitch? Am I done? Unfamiliar with problem solving of this nature, however you are the expert. I thank you for your time.

If their email service @juniper.net is not responding you would see the messages you started this thread with.