Weddingbee boards

So I bought the kits from Micheals for my wedding invitations. Here's the picture. It comes with the actual page for the invitation, labels for the big brown pretty envelope and RSVP card and envelopes.

Here's my question. Do I need to get ANOTHER envelope to put this one in to protect it? It's heavy duty stuff really, and comes with the seals and everything. If I do use another envelope, do I need a liner? It really would be an envelope in an envelope... I'm a bit confused.

Any help would be appreciated!