We’re seeing PostMark issues as well (Started maybe June or May?). Two separate members of ours, using two separate app vendors, both of which seem to use Postmark. The only info I have third hand is “Timed Out waiting 5s for response to cmd=STARTTLS”. I can’t seem to find any indication of rejected connections from Postmark on my end. Firewall logging also shows all traffic flows allowed for the items that DO make it through.
Did you ever make any progress on your issue? Might these be related? (May 22-24th also sticks out as to some sort of change made, but I’m not sure if that was the app vendor or PostMark themselves.) From: Scott Q. <[email protected]> Sent: Wednesday, July 15, 2026 1:30 PM To: [email protected] Subject: [mailop] Issues receiving from Postmark If someone from Postmark is on the list..it seems we are having an issue receiving e-mails from you. Only error customers report is: smtp;400 KumoMTA internal: failed to connect to any candidate hosts: connect to 65.39.216.37:25 and read initial banner: reading banner: Error Connection closed by peer reading response to cmd=NONE Sample e-mail: X-KumoRef: eyJfQF8iOiJcXF8vIiwicmVjaXBpZW50IjoiY2hyaXNAaW5zdXJldGhlYm9hdC5jb20ifQ== You can message me off-list - thank you! Scott
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