Getting error message when adding new members/sending emails

I am getting the following error messages when trying to add new members or sending emails to established members through our site.  4991.toastmastersclubs.org/ . The email addresses are valid, verified, and in most cases have been established for years. The issues started within the last 10 days. 

Adding new members: 

1. Invalid/Non-functioning E-mail: NaumannChristR@JohnDeere.com (No advertised SMTP servers are accepting mail.)

Sending emails:Emails to the the following members were skipped
for the reasons listed below:Mark Barker (invalid/non-working email address)
Justin McCoy (invalid/non-working email address),Oliver Stone (invalid/non-working email address),Ellen Sjolund (invalid/non-working email address),Lisa M. Palmersheim, ACG, ALB (invalid/non-working email address),Marcus Jacobson (invalid/non-working email address),Carla Sato (invalid/non-working email address)
 

try it now.

It appears to be working now. Thank you.