The 11 Best letter Size Security Envelopes (2023 reviews)

There are several advantages of having a letter size security envelope. Let’s take you step by step, type by type, and find the best letter size security envelope for you.

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Our Top Picks:

Best Overall: Buy: Quality Park letter Size Security Envelope READ REVIEW

Best With A Window: Buy: Mead letter Size Security Envelope READ REVIEW

Best For So many Envelopes: Buy: Amazon Basics letter Size Security Envelope READ REVIEW

Best For protecting private Mail: Buy: Aimoh letter Size Security Envelope READ REVIEW

Best With address: Buy: Horchen letter Size Security Envelope READ REVIEW

Best With logo: Buy: Blue Summit supplies Nice Secure Seal READ REVIEW

Best For magnetic calendars: Buy: Aimoh super Secure Seal READ REVIEW

Best For company: Buy: Mead reasonable Price READ REVIEW

Best For Mailing Invoices: Buy: HERKKA letter Size Security Envelope READ REVIEW

Best With Most inkjet And Laser printers: Buy: HERKKA LONG LASTING SUPPLY READ REVIEW

Best For home: Buy: Blue Summit supplies letter Size Security Envelope READ REVIEW

Best Overall: Quality Park letter Size Security Envelope

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Compared with other envelope in this category, the quality park letter size security envelope has a design with broader appeal. These envelopes are first class, easy to use and letters fit nicely in them. It protects yourself and customer/client data with security features that keep personal information confidential while in transit. A beautiful white front allows plenty of space to write a name and address, while still leaving room for both a return address sticker AND proper postage. The peelable paper strip protects the adhesive from dust so your envelopes last longer in storage.

The Envelopes are secure for contents and seal holds well. The self-stick part works great too and no more licking envelopes. This is a good amount of envelopes for personal use without having to pay for a pack of. It is perfect for delivering checks via snail mail or drop off.

• Great quality and easy to use envelopes
• Perfect letter size, sturdiness/paper quality, adhesion
• Self adhesion is a great plus and works like a charm

Best With A Window: Mead letter Size Security Envelope

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Best part: mead letter size security envelope costs comparatively low and it is available to ship in 24 hours. These are envelopes for mailing letters of all kinds. It has a secure, marked inside, paper with a self seal flap. It can utilize lick-and-seal, peel-and-seal or even (gasp) tape-and-seal technology to secure the flap. The glue holds the top flap shut with minimal licking and the "security" pattern hides the fact that you're mailing a check.

These mead envelopes feature a security lining to maintain privacy of documents. They must be moistened to seal. The glue on the flap is a bit sparse. They are not seen through and the flap glues down when wetted.

• Easy use and no problem placing in printer
• Good brand reputation

Best For So many Envelopes: Amazon Basics letter Size Security Envelope

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The amazon basics letter size security envelope is specially designed for your daily usage and has all useful features. They're envelopes, perfect. It has security printing on the interior so nothing shows through. The envelopes are gummed near enough the ends of the envelopes to keep them fully closed. This is a very large box of envelopes. It will hold 3 or 4 sheets of tri-folded regular printer paper for mailing purposes. It is made from a printed paper so enclosed contents can not be scanned.

• Plain box of envelopes that work well for securing paperwork
• Correct size, good security printing and stays closed when sealed
• Good quality, and go through printer without wrinkling
• Lots of excellent quality (thicker) envelopes

Best For protecting private Mail: Aimoh letter Size Security Envelope

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We know from years of feedback from readers, customers and amazon sellers, what most people want in a convenient and appropriate envelope. The aimoh letter size security envelope is exactly that - it's a simple envelope that hits all the right notes. These are sturdy envelopes made from good stock. They are of good quality with no hint of flimsiness. It is perfect for ultra-secure personal mailing while protecting sensitive information. The self-sticking seals work very well. They are inexpensive and excellent for the value. These envelopes are made to hold checks. It is great for including in billing statements for customers to remit payment.

• Perfect size, thick enough to provide security
• Thick and durable envelope, adhesive is great
• Good brand reputation

Best With address: Horchen letter Size Security Envelope

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The horchen letter size security envelope is capable of outshining several other envelope featured in this list in overall features for the price point. These are thick and well-made, and work extremely well for privacy. They are stronger than most ordinary envelopes. The inside is printed with a gray pattern to help keep the contents private.

These are made with good quality paper and are sealed together well. The adhesive strip is wide and secures the oversized flap tightly. The envelope is not flimsy but it's made from good quality and the adhesive is perfect. This strong adhesive design will help protect your documents.

• Higher quality than typical envelopes, much thicker
• Ample size, covers contents completely, good quality and adhesion
• Peek proof and a good weight

Best With logo: Blue Summit supplies Nice Secure Seal

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If you often find yourself confused about appropriate and satisfactory envelope, blue summit supplies nice secure seal should be your first option for buying. These envelopes are designed for both laser and inkjet printers. They seal securely, yet are designed to open easily. It provides complete mail security. The paper is strong, peeling adhesive better than licking glue and the black privacy is wonderful.

These envelopes seal securely, yet are designed to open easily. It’s cleaner and does not spread germs from people who still lick their envelopes. The envelope does have a strip to peel off. It is perfect for secure everyday home and business mailing.

• Perfect choice with the adhesive strips andthickness of the paper
• Good for personal and small business
• Easy to use and sticks closed well
• Nice quality paper and peel and seal

Best For magnetic calendars: Aimoh super Secure Seal

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The aimoh super secure seal is capable of outshining several other envelope featured in this list in overall features in its price range. These durable, security envelopes make it through the postal system without fail. It is great for protecting private mail. The peel & stick glue is strong, and they stay closed in the mail. The closure actually sticks tightly, so a check would not fall out.

These envelopes are made to hold checks. They all sealed easily and stay sealed. It is perfect for the magnetic calendars.

• Thick and durable envelope, adhesive is great
• Perfect size, thick enough to provide security
• New and hot release

Best For company: Mead reasonable Price

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The mead reasonable price's superior materials makes sure that it ages well with use. These are the clear and logical choice for all of your envelope needs. The peel and stick makes it convenient and easy to use. They are thick enough that you can't see through it. To make matters worse, the glue allows the flap to be unpeeled without destroying the envelope, so if you are careful you can unpeel the flap, remove the contents, and reseal the envelope, all without leaving any sign that the envelope has been tampered with.

The peel-off seal is a nice touch. It works great with printer paper. It has the printed lining for privacy which works great.

• Good quality and adhesive works well
• Large enough to fit letters and bills
• Good brand reputation

Best For Mailing Invoices: HERKKA letter Size Security Envelope

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Herkka is known for creating pragmatic and minimalist envelope for people on the go, and its line of herkka letter size security envelope definitely falls in line with that reputation. These #9 envelopes have a black security print which is a must when mailing out checks. It is perfect for everyday business correspondence and large mailing tasks. It does not dry up over time and the adhesive stays for a long time. It is superior to any self sealing one with a strip. It works for billing statements plus it is great for the corporate world.

The adhesion works great and the box comes with so many. It is perfectly read everything that needs to be read, and nothing that doesn't need to be.

• Very crisp and professional looking evenvelopes
• Self seal is great so you don't need to lick them
• Good investment for long term

Best With Most inkjet And Laser printers: HERKKA LONG LASTING SUPPLY

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If you’re looking for the perfect security envelopes with professional security tint, and strong, quick seal strips, in a great value 500 envelope supply, perfect for everyday use, herkka #10 security tint envelopes are the perfect choice. It is ideal for standard business & legal documents and sensitive correspondence, manufactured with a windowless blank design allows for easy address printing or labels for mass mailing or to simply keep a bulk supply on hand for your home office.

The 10 security envelopes are designed with a premium security printed design to provide guaranteed privacy for your legal or business mail, offer the protection contents and sensitive information, a security tint makes envelopes hard to see through that ensures upmost privacy. There is coverage over the window, great envelopes. These envelopes stay sealed, are not transparent and can be stuffed easily with standard printer paper. It is great in laser printer. It is compatible with most inkjet and laser printers for easy printing.

• Large, windowless design measuring 4-1/8 x 9-1/2 inches
• Awesome value, good paper, great toner adhesion from the printer too
• Perfect for quick, mass business mailings

Best For home: Blue Summit supplies letter Size Security Envelope

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The blue summit supplies letter size security envelope is suitable and reliable and fits well with your daily usage. A windowless envelope is the safest type of design, offering zero chance that your secure information will be exposed through transparent windows during transit. It’s simple to flip up the bottom flap and press down the top flap to seal. The smooth 24 lb white wove paper that creates a professional look and feel from out of the box all the way to your destination. If you get the window envelopes, the window will melt in a laser printer. There is the added benefit of not having to lick that nasty glue strip.

These are high quality & stick well. It is great for working from home and the adhesive is great.

• Wasted plastic strips from the peel and seal design
• Easy and affordable way to order
• Save time with easy to use flip and seal self-seal design