Problem

----You're trying to set up a flow with Email Notification for an external partner and you are getting this error:

GI TransportReport: Event = 'MessageRejected' RejectReason = 'com.cyclonecommerce.tradingengine.transport.FatalUnableToProduceException:

Error sending message to: mailto:xxxx.xxx@yyy.com - SMTP Command: .

Resulted in error reply from SMTP Server: 550 5.7.1 Client does not have permissions to send as this sender'

Resolution

---- This error is related to the external SMTP server configuration.

--- Here some steps for Exchange Management Console. Do the same on your SMTP server in order to grant the Send As permission.

https://www.sonicwall.com/en-us/support/knowledge-base/170504745287664