Invitation emails bypass organizer's Sent folder + silent failures with no user feedback

[mmaudet]

Context

Two problems seen in production when an organizer sends an event invitation to an external attendee (e.g. herve.grandjean@canut.org):

1. No trace of the invitation in Twake Mail "Sent" folder, even though the calendar back-end did dispatch the invitation.
2. The external attendee never received the mail and the organizer has no feedback about the failure.

1. Invitations bypass the organizer's Sent folder — by design, but very confusing

calendar-smtp/src/main/java/com/linagora/calendar/smtp/MailSender.java:142 delivers via a system SMTP relay account (auth from smtp.username / smtp.password — see MailSenderConfiguration.java:43-59). No JMAP submission on behalf of the organizer, no reference to "sent mailbox" / "outbox" / JMAP anywhere in calendar-smtp or calendar-scheduling.

Consequence: invitations never appear in the organizer's Twake Mail Sent folder. The organizer can't verify the mail was actually queued for delivery, can't reply-thread from Sent, can't audit their outgoing scheduling traffic.

Two acceptable outcomes:

• (preferred) send via the user's JMAP submission so the mail lands in Sent — the invitation is technically the organizer's outbound mail.
• (minimum) clearly state in the UI/help that calendar invites go via a system relay, and add a "delivery log" visible to the organizer.

2. External delivery failed silently

Pipeline observed in code:
esn-sabre AMQPSchedulePlugin → exchange calendar:itip:localDelivery
→ ItipLocalDeliveryConsumer.java:82 (splits N-recipient message into N single-recipient messages)
→ ItipEmailNotificationPublisher.java:85 → exchange calendar:event:notificationEmail:send
→ EventEmailConsumer.java:76 (routes by iCalendar METHOD)
→ EventMailHandler.handInviteEvent() (EventMailHandler.java:409)
→ MailSender.send() (MailSender.java:142)

Any failure at any hop lands in a dead-letter queue (tcalendar:itip:localDelivery:dead-letter, tcalendar:event:notificationEmail:send:dead-letter) with zero user-facing visibility.

Expected

• Either integrate JMAP submission so invitations land in the organizer's Sent folder, or provide an explicit in-app notification when calendar mail delivery fails (bounce, SMTP relay rejection, dead-letter).
• Document the current SMTP relay architecture so support can troubleshoot: which config keys must be set, which queues to check, which logs to grep.

Steps to reproduce

1. Organizer with a Twake Mail account creates an event and adds one internal + one external attendee.
2. Check Twake Mail Sent folder → invitation is not there. (Bug 1)
3. If the external attendee never receives the invite, look at the DLQs on the RabbitMQ instance to see if the message was dropped, and the SMTP relay logs to see if delivery was rejected. (Bug 2)

Files

• calendar-smtp/src/main/java/com/linagora/calendar/smtp/MailSender.java:142
• calendar-smtp/src/main/java/com/linagora/calendar/smtp/MailSenderConfiguration.java:43-59
• calendar-amqp/src/main/java/com/linagora/calendar/amqp/ItipLocalDeliveryConsumer.java:82
• calendar-amqp/src/main/java/com/linagora/calendar/amqp/ItipEmailNotificationPublisher.java:85
• calendar-amqp/src/main/java/com/linagora/calendar/amqp/EventEmailConsumer.java:76
• calendar-amqp/src/main/java/com/linagora/calendar/amqp/EventMailHandler.java:409

Reported from production feedback on Twake Calendar, downstream of Benjamin's forwarding.

[chibenwa]

That's controversial: for instance Gmail for instance do not do it.

yet

As such I would lean on not implementing this as its not standard.

Benjamin Andre tends to agree.

@Bobpodvalnyi can you please see if Outlook does this ?

[chibenwa]

For in sent mailbox calendar invite copy while GMail do not do it, Outlook does.

So do we really want this?

If we need to implement this:

• calendar sets a specific header
• When this header is present we add a copy to the sent folder mailbox in tmail

This needs:

• 01 PR in calendar
• 01 PR in the base helm chart
• release the helm chart across envs

So ~1 week to pull it off