A digest is one or more mail messages encapsulated in a single message.
VM supports digests by providing a command to "burst" them into their individual messages. These messages can then be handled like any other messages under VM.
The command * (vm-burst-digest) bursts a digest into its
individual messages and appends them to current folder. These
messages are then assimilated into the current folder using the default
grouping. See section Grouping Messages. The original digest message is not
altered, and the messages extracted from it are not part of the on-disk copy
of the folder until a save is done.
If you give a prefix argumet to vm-burst-digest, it will attempt
to cope with non-RFC 934 compliant digests. If vm-burst-digest
seems to be breaking digests at inappropriate places, most likely the
digest is not compliant with the standard. In this case try using the
prefix arg.