This post is meant to serve as a little guide for USPS related policies surrounding wedding invitations and pretty much any piece of mail. However, I am not a USPS employee, so for all your official questions please refer to USPS.com or visit your local USPS location.
Mailing your invitations seems pretty easy and straightforward right? Well, not so much unfortunately. Each Post Office has a mind of its own meaning each office operates differently. (Amazing, right?) If you have chosen to mail your own wedding invitations, here's a a few things you should keep in mind:
Know the Size and Weight of Your Envelope
The USPS Standard Letter-Size postage rates as of January 2020 are $0.55 for items under 1 ounce and $0.15 for each additional ounce. Here are some other things to consider:
Wax Seals and other embellishments may affect the thickness/weight of your suite and will require at least $0.15 in additional postage. There are a lot of variables when it comes to calculating the “thickness” of your suites and your postal clerk should inform you at the time for an estimate.
Destination Matters: International addresses will require additional postage. You can get a base estimate for international letter postage rates at usps.com.
Square envelopes are considered “odd-sized” and may require additional postage.
Hand Cancel your Invitations
If you’ve opted not to have your stationer mail your invitations for you, I highly recommend taking your invitations inside the post office and hand-canceling your postage especially if you have a wax seal, ribbon, or vintage postage. If you are unsure what hand canceling means, instead of machine processing, you can request that your envelopes be processed by hand. Your postal clerk will stamp each postage on each envelope, with a special rubber stamp noting the current date and the postal location. This bypasses the need for the envelope to be sent through their sorting machines. Also, if you have calligraphy addressing, hand canceling can avoid the machines reading the address incorrectly. No matter the envelope type or embellishments, machine processing can leave unsightly marks on your envelopes and hand-canceling your postage bypasses this issue. (Some clerks will tell you they don’t hand-cancel anymore, they’re wrong and you can ask to speak to the office’s manager. If at first you don’t succeed, ask for a second opinion or go to another post office.)
Not All Your Invitations Will Make it to Their Destination
The first thing you can expect when mailing your invitations is that not all of them will make it. As with any mass mailing, it is expected that 1-3% of the mailed pieces may be marked undeliverable. Thousands of letters and packages are shipped worldwide going through people and sorting machines every single day meaning there are multiple things that can go wrong along the way. This is why it is so incredibly important to order extras in case you have to send out a few invitations again. Normally 20% extra of your wedding invitation count will suffice. Something else to consider is that some of the invites will make it to their destination the very next day and some won't be delivered for weeks! This shows that the rules are arbitrary, and that sometimes you can just get lucky.
Use More Postage than You Think You'll Need
There are many factors you need to consider when adding postage to your suite. One thing I recommend before sticking any postage on the envelope is to take one of your invitations (embellishments and all) to the post office and ask them how much postage they would recommend. Not only do I recommend getting one opinion, I recommend asking another person from the same post office or go to a different post office to get a second opinion. If you have anything that makes your suite bulky (wax seals, ribbon, extra thick paper) expect to add on extra postage. If your envelope weighs more than an ounce, expect to add extra postage. The post office can get a little nit picky with a few things so it's better to add more than enough, rather than just enough or not enough and then your guests recieve an envelope with a "21 cents due" notice. Yikes!
These are only a few examples of what you need to be prepared for when mailing wedding invitations! Hopefully, this has helped you understand the mailing process a little better and has mentally prepared you with what to expect when mailing your wedding invitations.