Forwarding email doesn't include the forwarded message

When forwarding an email without "mime replace" the forwarded message is to be attached on the server by Z-Push.

Apparently the Nine client uses the long-id feature in the source message which is not yet being parsed.

Steps to reproduce:

1. use nine client
2. open any message
3. click forward
4. send message

Result: the recipient only receives the "forwarded from..." headers sent by the mobile, but not the original message

Expected result: "Forwarded from..."-headers and the original message should be sent.

Seen on:

Device type: Android
UserAgent: Nine-OnePlus7Pro_EEA/PKQ1.190110.001
Device Model: GM1913
Device friendly name: OnePlus7Pro_EEA
Device OS: Android 9.1906160746
Device OS Language: English (United States)
Device Operator: Vodafone.de
ActiveSync version: 14.1

Z-Push: 2.6.0.alpha1+0.91f1f05a-0