Changed to use alias for club website URL - email not working

We are getting rid of our old domain name - pitmclub.org and instead want to use club4535.toastmastersclubs.org. I made the changes but now when I send an email to all members using members@club4535.toastmastersclubs.org I get the following error. The website url works.

The following message to <members@club4535.toastmastersclubs.org> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-'5.7.1 <members@club4535.toastmastersclubs.org>... Relaying denied. Proper authentication required.'

Is there something else I need to change in the website settings or is it a matter of waiting until the old domain name is deleted?

Thanks in advance!

John Bishop
Pine Island Toastmasters Club 4535
club4535.toastmastersclubs.org

John,

Try members-4535@toastmastersclubs.org

Thanks for the quick reply! Was hoping it was something simple. I was able to send using members-4535@toastmastersclubs.org.

John