Hi,
This warning is not a problem. It just means that file_get_contents is not available on your server to check the catpcha answer once the form is submitted. In that case, the plugin automatically switches to cURL.
And even if it was a problem, it couldn't generate that "invalid address" error.
Let's take a step back:
When someone registers you either have one or two emails sent.
The first one is sent to the email address entered in the registration form. So that means you could get that error if you had an issue with either:
- the email address entered in the form
- the email address "from" entered in the HikaShop configuration
- the email address "reply-to" entered in the HikaShop configuration
- the email address "bounce" entered in the HikaShop configuration
- the email address "form" entered in the settings of the "user account" email via the menu System>Emails
- the email address "replay-to" entered in the settings of the "user account" email via the menu System>Emails
- the email address "CC" entered in the settings of the "user account" email via the menu System>Emails
- the email address "BCC" entered in the settings of the "user account" email via the menu System>Emails
Similarily, if you activated the notification to the admin in the settings of the Joomla user manager, a second email is sent to the admin. So that means you could get that error if you had an issue with either:
- the email address "from" entered in the HikaShop configuration
- the email address "reply-to" entered in the HikaShop configuration
- the email address "bounce" entered in the HikaShop configuration
- the email address "form" entered in the settings of the "User account administrator notification" email via the menu System>Emails
- the email address "replay-to" entered in the settings of the "User account administrator notification" email via the menu System>Emails
- the email address "CC" entered in the settings of the "User account administrator notification" email via the menu System>Emails
- the email address "BCC" entered in the settings of the "User account administrator notification" email via the menu System>Emails
So that's all the things you should check. I don't see anything else.