Relay server queing email to Exchange servers

Issue: “exchange.domain.edu Temporary error returned by SMTP partner. smtp;452 4.3.1 Insufficient system resources
Synopsis: Relay servers actually make the smtp connection, but exchange server/s responds to relay with a hold on message because it's busy
Resolution: Checked queue drives on exchange servers. Found out one of the servers, had 4% disk space remaining. Had to delete some log files to create space
By so doing, disk latency reduced and queues on relay servers cleared​