I am trying to set up a workflow with CiviCase to automatically file clients' responses on their respective cases.
According to the documentation, mails arriving in the e-mail-to-activity-Mailbox, containing the pattern [case #123] in their subject line, get automatically filed under the respective case (123 in this case) as an activity ('Incoming E-mail').
This is all working fine so far regarding the overall process. However, the contents of the incoming mail is not visible in the 'details' section of the activity. An attachment with the mail gets created, but with the extension '.unknown'. I can download this attachment, manually select a program to view it (e.g. a text editor) and (only) the body of the mail gets displayed as plain text, the header info seems to be stripped off. This behavior happens for html mails as well as plain text mails.
What I originally expected was something like a plain text representation of the mail under details, the same way as it is handled with outgoing mails. And the attachment should ideally contain the unaltered and entire mail, including the header information (date/time, recipients) and have a filename extension which could be recognized by a mail client after download (e.g. .eml).
My main question for now: Is this the intended behavior (then I can arrange to live with it, since I am quite happy with the overall process) or am I missing some configuration settings somewhere?
(Using CiviCRM 5.13.1 and Wordpress 5.1.1)