Just a note. The "fetch_by_chunks" option indeed works as a workaround.
Since there is no option in Thunderbird to reload a single message,
you will have to reload the whole folder. To do so, go to the folder Properties
and select "Repair Folder".
I believe this is indeed a bug with Exchange (all versions including 2010),
but it's good to have this workaround listed here because it looks like MS is
not going to ever fix that.
Just a note. The "fetch_by_chunks" option indeed works as a workaround.
Since there is no option in Thunderbird to reload a single message,
you will have to reload the whole folder. To do so, go to the folder Properties
and select "Repair Folder".
I believe this is indeed a bug with Exchange (all versions including 2010),
but it's good to have this workaround listed here because it looks like MS is
not going to ever fix that.