Fax service forces me to supply an email address which it then discloses to the fax recipient. What’s my fix for this?

The fax service demands an email address for confirmation purposes. I give a disposable address using a service that lets me choose the username portion. So I choose an address like dysfunctionaladdress@disposablebox.xyz. Then I use that disposable acct to confirm the fax.

The fax service discloses the email address to the recipient. I would expect my email address wording would make it loud and clear to the recipient that it is unfit for sending email. But motherfuckers use it anyway! I suppose they are too lazy to send snail mail to the address I provided. So then their response to dysfunctionaladdress@disposablebox.xyz is publicly shared with the world. And not me, generally, because I don’t return to the disposable box.

It’s such a shit-show. How can I control for this? I need a fax service that does not force exposure of email address to recipients. I don’t mind paying to send a fax so long as it’s a pyg (pay-as-you-go) service. I can only find fax services that require a plan with monthly payments.

Any suggestions? The whole point in using a fax is to prevent the recipient from reaching me over email.