To be able to send an SMS you need to authorise, in the SMS control panel the senders email address.

If you would like to authorise ALL email addresses sent from your domain, you are able to add a wildcard using this format;

*@my_domain.com

This should be added as part of the SMS control panel settings (for further details on this take a look HERE)

This will authorise any email address that has your domain after the @ symbol.

IMPORTANT : If you add a wildcard, DO NOT add specific addresses from the same domain. For example, if you add '*@my_domain.com' you would not also add 'info@my_domain.com' or 'admin@my_domain'. Doing so can cause problems.