550 5.1. 1 means that the recipient email server believes that the #email address does not exist at the destination #domain, and therefore has no way to deliver it. Unless you simply made a typo in the email address, this is not something that you can fix, and must be addressed at the other end. >> https://ibmimedia.com/explore/550-5-1-1-recipient-address-rejected-exchange
#exchange
