By default, captcha emails are sent with the domain email @humail.link. The correspondent receives a message from the address humail@humail.link.
You can change this setting to display the client domain name instead.
For example, below, we select "humail@yourdomain" through Filtering=> Configuration => "Humail active".
We have taken the secuserve.com domain as an
example. Upon receiving the captcha control message your correspondent sees
humail@secuserve.com