6 Postage Pointers

Stuff your invitation envelopes.
Leave yourself enough time to assemble, address and stuff all those envelopes. Your planner can handle this task for you (or your stationer may do it for an extra fee), but if you (and the lucky friends you've recruited) are doing the stuffing, here's the traditional order for assembling your invitations:

    The invite goes on the bottom; then stack your enclosures on top in order of largest to smallest (the smallest goes on the very top of the pile).
    The RSVP card should be tucked into the flap of the reply envelope (so the flap covers part of the text).
    Place everything in the inner envelope so the text is facing outward -- that way guests can read the invitation as they take it out.
    Put the unsealed inner envelope inside the outer envelope with the guests' names facing outward.

Note: Inner envelopes aren't required and are usually reserved for traditional invitations.

Stamp the RSVP envelopes.
You don't want your guests to pop their envelopes in the mail without a stamp or to make them pay for postage to RSVP to your event. Make it easy for them to send back their RSVPs: By putting postage (and a return address) on the RSVP envelopes, you'll ensure they get back to you (or whoever is in charge of the guest list) without a hitch. A standard stamp will do for these smaller cards that don't weigh much.

Have your invitations hand-processed.
Machines at mail centers can only process certain envelope shapes and sizes -- generally rectangles that are a minimum of 3.5 by 5 inches to a maximum of 6.125 by 11.5 inches. If your envelope is an odd shape (say, square), even if it falls within those dimensions, you may end up paying a 20 cent non-machinable fee per envelope. With larger invites (more than 3.5 ounces or bigger than 6.125 by 11.5 inches) -- like a boxed invitation -- you won't have to pay the surcharge to hand-process them. But even if your invitation doesn't meet the non-machinable criteria, consider paying the extra fee to have them hand-processed anyway -- it will guarantee that your mail will be sorted by hand rather than by a machine, which can bend or even ruin your invites. Another way to go is hand-canceling (just a stamp that says your mail is processed). While this option is free, check with your local post office first to make sure that it has the hand stamp. The only catch is that while most post offices try to keep hand-canceled mail separate from regular mail, there's no absolute guarantee that your invitations won't also go through the processing machines.

Weigh a complete invitation.
Before you pop your invitations in the mail, ask the post office to weigh a complete invite so you know exactly how much postage each one requires. This step may sound tedious, but the alternative may mean invitations returned for insufficient postage, which could throw your entire wedding planning timeline for a loop. Enclosures will increase your postage, so keep that in mind when you're deciding on extras like maps or reception cards.

Put a stamp on it.
After all the work you've put into your envelopes and invitations, don't ruin the cohesive look by sticking any regular stamp on it. TheKnotShop.com has cute, customizable stamps, and you can also browse special stamps on USPS.com. Or work with your stationer to design custom postage that matches your invitation design or colors. And don't forget to order enough for your RSVP envelopes too!

Mail them out.
You're done! Send out your invitations six to eight weeks before the wedding -- or 10 to 12 weeks in advance if you're having a destination wedding.

source:http://wedding.theknot.com