Triggered by a message like this:
[2025-10-27 16:06:14] production.INFO: BEGIN:VCALENDAR
VERSION:2.0
PRODID:-KolabiRony DAV Server 0.4.3SabreSabre VObject 4.5.7//EN
CALSCALE:GREGORIAN
BEGIN:VEVENT
UID:040000008200E00074C5B7101A82E00800000000C0587388AF1AD901000000000000000
010000000CB8B1E812888704AA9AB7204FE9490B7
DTSTAMP:20230320T125029Z
CREATED:20230124T100802Z
LAST-MODIFIED:20230320T125029Z
DTSTART;TZID=Europe/Berlin:20230110T110000
DTEND;TZID=Europe/Berlin:20230110T120000
...
ATTENDEE;CN=attendee;PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;CUTYPE=
INDIVIDUAL;RSVP=TRUE:mailto:attendee@example.com
ORGANIZER;CN=organizer@example.com:mailto:organizer@example.com
X-MOZ-LASTACK:20230214T061743Z
X-MICROSOFT-CDO-IMPORTANCE:1
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
X-MICROSOFT-DISALLOW-COUNTER:FALSE
X-MS-OLK-AUTOSTARTCHECK:FALSE
X-MS-OLK-CONFTYPE:0
X-MOZ-SNOOZE-TIME-1674554400000000:20230214T062243Z
X-MOZ-GENERATION:4
X-ACTIVESYNC-DTSTAMP:2023-03-20T12:50:37+00:00
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER:-PT15M
DESCRIPTION:....
END:VALARM
END:VEVENT
BEGIN:VEVENT
UID:040000008200E00074C5B7101A82E00800000000C0587388AF1AD901000000000000000
010000000CB8B1E812888704AA9AB7204FE9490B7
DTSTAMP:20230320T125029Z
CREATED:20230124T100802Z
LAST-MODIFIED:20230320T125029Z
DTSTART;TZID=Europe/Berlin:20230221T110000
DTEND;TZID=Europe/Berlin:20230221T120000
RECURRENCE-ID;TZID=Europe/Berlin:20230221T110000
...
X-ACTIVESYNC-DTSTAMP:2023-02-15T20:09:09+00:00
ORGANIZER;CN=organizer@example.com:mailto:organizer@example.com
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER:-PT15M
DESCRIPTION:...
END:VALARM
END:VEVENT
END:VCALENDAR