You may receive a “failed email to fax” message after you attempt to send a fax, or a “recipient unknown” message if the recipient’s information is incorrect. These are legitimate error messages.
However, if you receive a large number of “failed email to fax” messages even if you have not sent any email-to-fax messages, it could indicate that your email has been compromised. If this happens to you, contact your network administrator immediately.
Additionally, RingCentral is investigating options for disabling email-to-fax functionality for customers who do not use this feature. If you detect fraudulent behavior involving your account, of if you would like the email-to-fax feature disabled, please contact RingCentral Support