retry timeout exceeded

Reporting-MTA: dns; 174-138-x-x.cprapid.com Action: failed Final-Recipient: rfc822;f1de11c069f6c4391a61c04b0548b694c2c3cbc4@multirbl.valli.org Status: 5.0.0 Remote-MTA: dns; relay.domain.net host relay.domain.net [x.x.x.x] Any advice how to resolve this issue?