Comment 1 for bug 266866

Originator: NO

Perhaps you didn't search well enough, or perhaps we just hide or don't
describe the option in these terms, but the Non-digest
options->scrub_nondigest option in the list admin interface will do what
you want. It will apply the same process that is applied to the plain
digest to individual messages.

The only problem is this is a list option, not an individual subscriber
option.