Help please... Addressing Envelopes

Hi,

I need to know... if I am inviting someone with a guest, on the outer envelope, should it be:

Ms. Jane Smith and Guest
123 Main Street
Main Street, MS 22222

-or-

Ms. Jane Smith
123 Main Street
Main Street, MS 22222

and on the inner envelope it should say:

Ms. Smith and Guest



Thanks

The outer envelope should just sya Jane Smith...unless you know her guest's name, then you can put both names

ETA: According to Emuly Post:

'If, for example, a close frind is invited and the brie and groom want her to bring a guest (whose name they don't know), the outer envelople is addressed to the friend and the inner envelope reads' Miss Smith and Guest'.

outer is jane smith
inner ms smith and guest
unless she is a close friend then it is ok to write
jane and guest
( that is from my guide for the stupid bride )

Thanks girls!!!!