Choose the Right Security Envelope
A security envelope has a printed pattern on the inside that makes the contents more difficult to read through the
paper. The right choice depends on the document, the location of its address fields, the sealing method and whether
the envelope will pass through a printer or inserting machine.
No-Window Security Envelopes
Choose a no-window style when addresses will be printed directly on the envelope or applied with a mailing
label. These provide an uninterrupted paper face while the interior tint helps reduce visibility through the stock.
Single-Window Security Envelopes
A single window displays the recipient address printed on the document inside. Confirm the window size and
position against your invoice, statement or form before ordering.
Double-Window Security Envelopes
Double-window envelopes display both return and recipient information from the enclosed document. They are
commonly used for checks, invoices and recurring accounting correspondence.
Self-Seal Security Envelopes
Self-seal, Pres-Stik and Kwik-Tak closures eliminate the need to moisten the flap. Traditional gummed envelopes
remain an economical choice for routine and machine-assisted mailing operations.
Security Envelope Sizes and Common Uses
| Envelope size |
Common applications |
| #6-1/4 and #6-3/4 |
Reply mail, compact statements, small documents and specialized office correspondence |
| #7 through #8-5/8 |
Checks, statements, financial forms and specialized business documents |
| #9 |
Reply and remittance mail designed to fit inside many #10 outgoing envelopes |
| #10 — 4-1/8 x 9-1/2 |
Invoices, statements, checks and letter-size documents folded into thirds |
| W-2 and 1099 formats |
Tax forms requiring specific single- or double-window placement |
| 9 x 12 catalog |
Full-size documents that should be mailed without folding |
What Security Tint Does—and Does Not Do
Blue, black and crosshatch interior patterns help obscure text and numbers that might otherwise show through white
paper. This makes security-tinted envelopes useful for payroll information, financial correspondence, customer
statements and other mail where ordinary paper opacity may not be sufficient.
A printed privacy tint is not the same as a tamper-evident seal, tracking service or regulatory certification. If your
mailing requires a particular compliance, tamper-evidence or chain-of-custody standard, confirm those requirements
separately before selecting an envelope.
Check Window and Printer Compatibility
Window position varies by product. Compare the listed window dimensions and placement with a printed sample of your
check, invoice, statement or tax form. For laser printing or high-volume inserting, select an envelope specifically
identified as laser-compatible, Digi-Clear or machine-insertable rather than assuming every window material will work
with heat or automated equipment.
Security Envelope FAQs
What makes an envelope a security envelope?
Security envelopes have a printed interior privacy pattern that helps prevent text and numbers from being easily
read through the paper.
What is the most common security-envelope size?
#10, measuring 4-1/8 x 9-1/2 inches, is the standard choice for business letters, invoices and statements folded
into thirds. Other sizes are available for checks, reply mail, tax forms and unfolded documents.
Should I choose a window or no-window security envelope?
Choose a window envelope when the address is already printed on the enclosed document. Choose a no-window envelope
when the address will be printed on the envelope or applied with a label. Always verify window placement against the
document before ordering.
What is the difference between single- and double-window envelopes?
A single window normally displays the recipient address. A double-window envelope displays two fields, commonly the
sender and recipient addresses, from the check, invoice or statement inside.
Are security envelopes tamper-evident?
Not automatically. Privacy tint helps reduce show-through, but it does not by itself reveal whether an envelope has
been opened. Select a product specifically identified as tamper-evident if that feature is required.
Can security window envelopes be used with laser printers?
Only when the product is identified as laser-compatible or designed for the intended printing process. Standard
window film may not be suitable for the heat produced by some printers.
Are security envelopes sold in bulk?
Yes. Most products in this category are sold by the box for business purchasing. Check each product page for its
exact box quantity, since quantities vary by size and specialty format.