Invitation mails

iCalendar allows to add attendees to an event. The attendee receives an invitation email with an attached ics-file that he can directly insert into his calendar.

There are basically three possibilities, who should send the invitation mail:

Invitation sent by sync adapter

There are two problems implementing emailing into the sync adapter.

For one thing that would mean to implement an SMTP client and an IMAP client (to put the mails into the sent folder) and so additional configuration effort for each account on each device. An alternative would be to call the android mail app to send the mails manually. Unfortunately it is not easy to forward the attachment headers properly.

Second problem is that since CalDAV-Sync is running in the background and syncing periodically, it is not active at the moment you create an event. So the mail app would pop up at the next sync.

Invitation sent by server

Many servers support sending invitation mails. This is maybe the best solution because the server is able to update the events status when receiving an answer from an attendee. Also, mail configuration is only necessary once.

Invitation sent by client

There are also calendar apps that support invitation mails.