550 relay not permitted error when emailing support@wpsharks.com

I apologize if this is not the correct place to post.

I had an active support thread going with support@wpsharks.com. Upon replying to the thread several emails in, I am getting a 550 relay not permitted error.

I have tried with my personal email and a third email account, to the same results. All of these are gsuite accounts.

Thanks!