Email address constantly bounces back

Somehow fth does not like our member's email address. Please write me privately to ask for the email address. This is the error I get every time:
xxx@xxxxx.com 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. ***

Please provide your club number and the member's first or last name
Have you actually checked the email address? Make sure there are no blank spaces or a dot after the com

Yes, I have re-entered it and it didn't change anything. First name is member.
This is Club #2046288. Thank you.

Sorry - first name is Carl

There is no one with name of member.

Carl hosts his site in a datacenter that spams FTH frequently and IP was blocked.
I have removed the block for now.