rmail-read-label

rmail-read-label is an autoloaded Lisp function in `rmailkwd.el'.

(rmail-read-label PROMPT)

Read a label with completion, prompting with PROMPT.
Completions are chosen from `rmail-label-obarray'. The default
is `rmail-last-label', if that is non-nil. Updates `rmail-last-label'
according to the choice made, and returns a symbol.