When a user creates an account on Hackster.io, we run a series of validations. One of these checks is to make sure the email provided actually exists and is deliverable.
If you're receiving the above error upon signing up for an account, this could happen for a variety of reasons, but generally it comes down to your email domain's server configuration settings.
These validation services may give you some more information on the specific reasons why your email is unable to be verified. If you have the proper admin permission to do so, you may then use this information to help configure your email server. If you do not have these privileges, try reaching out to your email provider to see what options you may have.
Unfortunately, we are unable to bypass this step for security reasons. If all else fails, you may try creating a free Gmail account and using that to sign up on Hackster.io.