Ubuntu Bug Triager (GF) tested this in several versions of Thunderbird: 52.9.1 (64-bit) 57.0b2 (64-bit) 60.0 (64-bit) Same result as reported. The file only contains the LAST message from the selection.
Ubuntu Bug Triager (GF) tested this in several versions of Thunderbird:
52.9.1 (64-bit)
57.0b2 (64-bit)
60.0 (64-bit)
Same result as reported. The file only contains the LAST message from the selection.