Microsoft attachments arrive as winmail.dat files

### What Happened?

Incoming mails containing Microsoft files arrive as winmail.dat attachments. It seems that support for reading TNEF attachments is missing.

### Steps to Reproduce

Receive a mail containing a Microsoft attachment such as .doc or .xls files.
Instead of the correct file format, the attachment is delivered as a winmail.dat file.

### Expected Behavior

Incoming mails with Microsoft attachments arriving in the intended format.
Mails arrive in correct format in Thunderbird on same machine.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Secure Session (Wayland, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

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### Hardware Info