[Dovecot] 1.0.13: mail_extra_groups alternative syntax?

"Warning: mail_extra_groups setting was often used insecurely so it is now deprecated, use mail_access_groups or mail_privileged_group instead"

I use the following:

mail_extra_groups = mail nogroup

Because I have the real and virtual accounts.

What's the correct way to replace the above line? It seems that

mail_privileged_group only accepts one group, but I need two.

Any suggestion? Thank you!

-- Linux 2.6.24: Arr Matey! A Hairy Bilge Rat! http://u-br.net http://www.abusar.org/FELIZ_2008.html