DURASEAL™ Envelopes

DURASEAL offers secure, stylish, or custom envelopes for all your mailing needs. Maybe you need a secure envelope that delivers maximum protection for confidential documents. Perhaps you’re looking for something stylish that will make your mail piece stand out.

Or maybe you just need a simple, standard envelope for everyday business mailings. Whatever your business needs, Relyco has the right envelope for you.

Security Envelopes

DURASEAL Security Envelopes

Specially designed with check security in mind, our high security check envelopes protect your critical bank routing and account information with the use of an inside security tint and unique window positioning.

Protect Your Critical Check Information

Our high security check envelopes are specially designed with check security in mind. Unlike standard #9 and #10 window envelopes, our check security envelopes protect your critical bank routing and account information with the use of an inside security tint and unique window positioning. Our check envelopes are always in stock and ready to ship.

DURASEAL Check Envelope Features

  • Unique windows positioned slightly higher to conceal confidential bank account information
  • Inside security tint to protect your documents from unauthorized readers
  • Full gum flap for a complete, secure seal
  • Special design for optimum machine inserting
  • #10 single window and #10 double window reverse flap security envelopes, ideal for machine inserting when the mailing address is located on the bottom of the document
  • Imprinting in up to four colors on the front and/or the flap

Call 1-800-777-7359 or email info@relyco.com and we will help you with all envelope sizes, constructions, and materials available for your application.

Custom Envelopes

DURASEAL Custom Printed & Personalized Business Envelopes
Relyco custom printed business envelopes offer unlimited design flexibility and security options to create an envelope for virtually any application that not only looks great and enhances your brand, but protects your document.

Deliver Your Mail in Style

Whether you are simply looking to put your logo or address on your business envelope, or want to differentiate your mail piece by delivering in style, our custom printed envelopes offer unlimited design flexibility and security options to deliver a piece that not only looks great, but protects your document. We carry tons of envelope sizes and styles for virtually any application and are always ready to assist you in the creation your custom printed envelope.

DURASEAL Custom Printed Envelopes Features

  • Standard and custom window locations and sizes
  • Custom imprinting in up to four colors on front, back, & flap
  • Custom security tint available for security envelopes
  • Machine insertable envelopes
  • Standard gummed flap, latex, self-seal, clasp, string, and custom closures available
  • Union labels available
  • All envelope sizes, constructions, and materials available for your application.

Call 1-800-777-7359 or email info@relyco.com and we will help you with all envelope sizes, constructions, and materials available for your application.

Business Envelopes

DURASEAL #9 & #10 Business Envelopes
Your Everyday Envelope. Available in #9 and #10 envelope sizes, our standard business envelopes provide the perfect solution to meet your basic day-to-day mailing needs. #9 & #10 business envelopes are always in–stock and ready for immediate shipment. ALSO AVAILABLE: DURASEAL Envelopes for Memjet and other Inkjet Printers–see more.

DURASEAL Business Envelopes Features

  • Standard #9 and #10 sized business envelopes designed for optimum machine inserting
  • Optional inside security tint to prevent unauthorized reading
  • Additional stock & custom business envelope sizes and layouts available
  • ALSO AVAILABLE: DURASEAL Envelopes for Memjet and other Inkjet Printers–see more.
  • Call 1-800-777-7359 or email info@relyco.com and we will help you with all envelope sizes, constructions, and materials available for your application.
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Client Stories


We knew that having the right envelope was important—and we knew that our most valuable resource, as always, was Relyco. The team at Relyco is extremely responsive and customer focused, with the expertise to know exactly the right solutions to meet our needs.

Cook Illinois Corporation logo
Assistant to the President and Chief Financial Officer, Cook Illinois Corporation
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