Flat Envelope Print & Mail Services
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Advantages of Flat Envelopes
Capture the attention of your recipient with large flat sized envelopes (i.e. 9 x 12 or 12 x 15 large envelopes) & make sure your direct mail campaign has a 100% open rate.
Professionally mail your printed materials and documents to display a sense of importance in the oversized flat envelopes.
Large flat, jumbo envelopes creates the opportunity to include many inserts of letters, flyers, catalogs, folders, business cards and more (no folding is necessary).
Large flat envelopes come in many different sizes & envelope types from bubble/padded mailers, standard 9 x 12 envelopes, custom flat envelopes & more.
USPS offers discounted postage savings for bulk mail campaigns that utilize large flat envelopes. Partner with an expert mail house like the Addressers to minimize your costs & maximize your campaign’s effectiveness.
Why Should Your Partner With The Addressers?
Years of expertise in postage savings and cost-effective solutions for your mail campaign.
Fast turnaround & in-house print capabilities to never miss another deadline again.
Turnkey print & mail services for large flat envelopes & the inserts
Fully customizable direct mail campaigns based on our client’s needs, no two campaigns are the same.
Transparent communication and seamless step-by-step process for your entire flat envelope campaign.
How Can I start a large envelope print & mail campaign?
Looking to begin the process for your large envelope bulk campaign? Contact our team today & the Addressers can finalize your flat envelope job in just a few simple steps, please see below:
STEP 1: The Mailing List
Would the mailing list be provided on your end or would you like the Addressers to source the list?
Our team will clean your list and verify the addresses to ensure the highest rate of deliverability. We’ll also make sure to qualify your list for the lowest postage rates available to minimize your costs.
STEP 2: Producing/Receiving the Printed Materials & Inserts
What would the inserts be for each flat oversized envelope? Would you provide any printed materials?
We can include most mail inserts from letters, catalogs, booklets. folders, pennants & more as long as they are not too heavy & have even thickness.
What type of oversized envelope would you like to use? Would you provide the flat envelopes or would you like us to recommend & provide it?
STEP 3: Finalizing Your Job
Our team and our hands-on approach will communicate the best solution for your flat envelope campaign. We’ll also discuss best solution for your large envelope campaign, confirm the quote, turnaround times & estimated in-home dates to finalize your job.
In just a few days, we’ll have your flat envelope & letter campaign out in your recipients’ mailboxes. Partner with the best today. Don’t take our word for it. Read a few of our 5-star Google customer testimonials!
Frequently Asked Questions About Flat Envelopes
Can we provide the Addressers with large flat envelopes that are already sealed?
Yes you can. Our team takes pride in the flexibility to receive your jumbo envelopes that are already sealed and all the inserts you’d like to include as well. They can even be addressed or you can have us address them for you based on your list. We’re not required to print and provide the envelopes, so let us know what you need from us and we’ll get it done. Reach out to our team today regarding your large flat envelope campaign.
Learn more about our addressing services here.
What is considered a large flat envelope for direct mail?
Flat envelopes are envelopes that are sized 9 x 12 or 12 x 15 and where there is no folding required for the inserts. These oversized envelopes are fantastic for documents, catalogs, kits, or large # of pages that you do not want to fold. They are not only eye-catching but will also protect your inserts.
These larger flat envelopes will qualify for a higher postage rate than your standard letter mailing. The postage is higher for flat envelopes but an expert mail house will be able to qualify you for discounted postage rates.
What is considered flat postage for direct mail?
Your campaign will qualify for the discounted flat postage if it hits one of these criteria: mail piece or envelope is larger than 6 x 11, or thicker than 1/4 inch, or heavier than 3.5 oz. And your max size is 12 x 15, it cannot be thicker than 3/4 inch and you cannot have uneven thickness or be over 16 oz. Any of these would require you to pay a higher postage at the package/parcel postage rate.
Speak to our team today, and we’ll advise the best postage options for you and your campaign, and we’ll even provide suggestions for ways to lower your postage.
What are 9 x12 or 12 x 15 large flat envelopes typically used for?
Oversized jumbo envelopes are fantastic for any direct mail inserts, letters, or documents you want to keep unfolded. Direct mail inserts include large catalogs, posters, certificates, employee kits, welcome packets and more. We have clients who utilize these large flat envelopes for marketing purposes but also to protect the integrity of the inserts.
How much does it cost to mail out large 9 x 12 envelopes?
Flat postage as of January 2026 is $1.185 for standard class under 4 oz. First class flat postage is higher and depends on the weight of the envelopes with the inserts. For example, flat postage first class is $2.578. Please reach out with your specs and our team will get you a quote for your oversized jumbo envelopes today.
Does the Addressers utilize the USPS for these flat envelope mailings?
Yes we do. We have the mailing permit with the USPS that allows us to offer discounted postage rates for these oversized envelopes that we highly recommend taking advantage of. Our expertise will allow us to advise the lowest postage rates for your flat mailing campaigns.
Can you provide tracking with flat envelope campaigns?
Yes there is tracking available for certified mail campaigns or for campaigns sent with TrackMyMail services. These typically come with an extra fee. We also provide other proofs of mailing such as certified mail services or postal receipts for these large envelope campaigns.
Can a bubble mailer or padded envelope qualify for the flat postage rates?
Yes you can, as long as the mailer as a whole is under 3/4 inch thickness, not lumpy and even thickness & less than 16 oz, it should qualify for the flat postage rate that is much more discounted than package postage and parcel mailing rates. If you have any questions regarding what postage your large flat envelope campaign would qualify for, please reach out and we’ll get you quoted.
Why should you outsource a bulk campaign with flat envelopes?
In general, most direct mail campaigns will include the preparation of the addresses, printing of materials/inserts, affixing postage & mailing which can be quite tedious, time consuming & expensive for companies and organizations, especially without the postage knowledge and understanding of fulfillment and mailing of large flat envelopes. Our team takes pride in being able to quickly fulfill and mail large flat envelope campaigns for our clients as a one-stop-shop and at the same time, we’ll make sure to minimize your fees. From standard white 9 x 12 envelopes to larger bubble flat 12 x 15 mailers, we’ll make sure to minimize your costs and maximize your results.
We’re very proud of our reputation, check out a few of our customer reviews!
How many pages can you fit in a large flat envelope?
It depends on the inserts, but we have found that 40 pages or so of standard letter stock will be able to fit in an envelope and not be too squished. To be certain, please reach out to our team, and we’ll discuss the best solution for your flat letter & envelope campaign.
What Our customers say about our services!
Ariel H, Phil Simon Clinic
Very helpful staff! They do a wonderful job and I would absolutely recommend using this company
Michelle M, Innovations for Poverty Action
The Addressers was a pleasure to work with from start to finish. I cannot say how many questions I had for them, and how much help and guidance I needed. They supported my organization through the process with patience and expertise, and the final product was beautiful, professional, and delivered in a much shorter timeframe than I expected. Justin was a wonderful rep. I would definitely work with them again!
Gabby M, Exclusive Automotive Group
I've had a great experience working with the Addressers for many luxury postcard campaigns. Their services are reliable, fast, and the staff is easy to work with! Shout out Justin!
Sara Beth B, TCEC Design
Love using the Addressers for our catalog mailing and fulfillment. Their team has always been helpful, kind, and easy to work with.