Receiving an "appears to be an invalid or non-working recipient email" message

Good afternoon Brian,

Are officers are getting the following message when we try to send a group message including our club President. 

" This 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.)
*** Please check the email address to make sure it is not misspelled. ***
If you believe this warning is incorrect, please visit  support.toastmastersclubs.org  and post a support request message."

I've confirmed the email address is valid and working.  Can you assist us?

Thanks,

The domain for  This email address is being protected from spambots. You need JavaScript enabled to view it.  is likely blocked by our server firewall... Brian will have to check that.

The IP that your email server is on tried to hack FTH and the block will not be removed.