I'm not sure when this started happening but Thunderbird (115.3.1, Linux) is no longer sending email invites to my invitees, even if some of those invitees are on my same host. as "Organizer" I do get an email notice to my personal email, which is the default attendee, with subject "Accepted: testing", and body, "mfoley@novatec-inc.com has accepted your event invitation.", but nothing is sent to the other invitees on the list. I checked the error console which showed these messages after I created the event: NotFoundError: No such JSWindowActor 'DevToolsFrame' 6 1701371572264 Toolkit.Telemetry WARN TelemetryStorage::_scanArchive - have seen this id before: 9c1e2d46-28f9-430d-86d7-398dd0ad3bdc, overwrite: false mailnews.smtp: error { target: TCPSocket, isTrusted: true, name: "NetworkTimeoutError", message: "Network", errorCode: 2152398862, srcElement: TCPSocket, currentTarget: TCPSocket, eventPhase: 2, bubbles: false, cancelable: false, … } SmtpClient.jsm:442:17 Not sure these apply to creating a calendar event. My server settings are fine, I can send and receive mail to the Thunderbird inbox without problem. I can send email from the Thunderbird client without problem. Any idea why I can't send event notifications to invitees?