E-mail address problem

Hello,
Something happened to one of our member's email address. When sending e-mail to them from our club web site, the error message comes: 
"reeToastHost Server <server@toastmastersclubs.org> 12:51 PM (27 minutes ago) 
to me

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. ***"

However, If I use my Gmail to send e-mail to this address - all is fine. 
The address (This email address is being protected from spambots. You need JavaScript enabled to view it.) on the website for this member is correctly spelled. 
Could you please help?
 

Looks like something changed at the beginning of June at windstream, they are using new IP for accepting email and we are receiving ...

He will have to contact his email supplier on why they are rejecting the email from toastmastersclubs.org