n.siegfried
16afc56c0a
smtplib calls getfqdn() on every connect when local_hostname is not given, and that reverse-DNS lookup blocks ~5s per send whenever DNS is slow or down (found when the office link dropped today: qa_gate_check's sink saw one mail per ~5s and its 12s waits timed out). Sends are sequential background tasks, so the stall compounded across a notification batch - in production a QA transition with a 3-person group would take 15+ seconds to finish mailing. socket.gethostname() never touches the network; the EHLO name is now computed once. Measured against the capture sink: 5.3s -> 0.3s for a two-recipient batch. Server mail path otherwise untouched. Item: CR-011 (the send path's transport). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>