Hello.
I'm using kubuntu 18.10, and using Kontact 5.8.3, also using akonadi-ews to contact local Exchange server.

I have several events per day and sometimes I want to see source mail and its attachments.
So when I receive an invitation and accept it, an event appears in my Kalendar. But if I click on event, I can't go back to an invitation letter (they are not automatically deleted by my settings).
I can click om event and see "attachment" word and a link like "CID:142B7A6D5991228B931F3FC76F2F502429907357@mycorpdomain.biz", and after clicking I see an error window, with message like can't find any app or service for handling CID blahblah.

Is it possible to view source mail or its attachments from kdepim calendar?

Hey, you may want to check my other thread with a similar (same root cause, I bet) problem: viewtopic.php?f=215&t=159990&p=414825#p414825 - namely my reply to myself with some sort of a workaround. You'd just need to double click the event in the timeline (to access the event details window) instead of single clicking the attachment file directly and go from there.

Hope it helps.