Thank you, Eric: this did the trick!

On Mon, 14 Jan 2002, Eric Thomas wrote:
> You need to make LISTSERV rehash the signup files. There is no command
> for this, because this must be done before the command processor
> starts. One method is to add SIGNUP_HASH="xxx" in go.user and restart
> LISTSERV. 'xxx' is the number of signup files you want LISTSERV to
> use, it should be a prime number and must be different from the
> current value (otherwise LISTSERV will not rehash).
>
>   Eric
>