The current Sender Email Address for the Due Date Overdue looks suspicious for customers, and due to its custom format (atlas-trk.prd.msg.ss-inf.net), it can be flagged as phishing emails. Users would benefit from having these emails address, but with a trusted known domain. Please adapt it to be sent from the Atlassian standard domain (e.g yourinstance.atlassian.net) so the receivers won't flag these emails as phishing.