Description Sender verify failed is an error which appears when trying to send an email.
Detail about issue:
550-Callback setup failed while verifying yyy@domain.com 550-Called: IP address MTA 550-Sent: MAIL FROM: 550-Response: 550 5.5.0 Sender domain is empty. 550-The initial connection, or a HELO or MAIL FROM:<> command was 550-rejected. Refusing MAIL FROM:<> does not help fight spam, disregards 550-RFC requirements, and stops you from receiving standard bounce 550-messages. This host does not accept mail from domains whose servers 550-refuse bounces. 550 Sender verify failed 550 5.0.0 Callback setup failed while verifying yyy@domain.com 503-All RCPT commands were rejected with this error: 503-Sender verify failed
This article describes how to fix this error.
Solution Go to Profile-> Session and enable 'Reject empty somains'.