1. What are the different kinds of envelopes?

• Banker Envelope
  This envelope is distinguished by a triangular flap on the long edge.
• Baronial Envelope
  This envelope has a large triangular flap. It is commonly used for invitations/greeting cards.
• Booklet Mailer
  This envelope is distinguished by a triangular flap on the long edge (for ease of inserting and taking out documents). It is usually A4 size and has a window.
• Business Reply Envelope / Return Envelope
  The special feature about the Business Reply Envelope is that the postage has already been paid by the sender. It is used for correspondence that requires the receiver to reply e.g. subscriptions, bill payment, etc.
  
  With the Return Envelope, the address of the sender has been printed onto the envelope but the receiver will still have to attach a stamp in order to mail it.
• Catalogue Envelope (also known as Coin Envelope)
  This envelope's open flap is at the long end of the envelope to make inserting documents easier.
• Clasp Envelope
  This is a Catalogue envelope with a metal clasp to close the envelope temporarily.
• Coin Envelope
  This is a small Catalogue envelope.
• Document Envelope
  As its name states, this envelope is used to send documents securely. It has seams either on the top or side.
• Eyelet String Envelope
  Eyelets are attached to the envelope's back. A string is threaded through the eyelets to close the envelope shut. This envelope is useful for sending bulky correspondence or documents.
• Insert Flap Envelope
  The flap is designed to be inserted into the envelope.
• Open End Envelope
  An open end envelope is a kind of envelope in which the opening flap is located on the shorter side of the envelope. Document and catalogue envelopes are examples of an open end envelope.
• Open Side Envelope
  An open side envelope is a kind of envelope in which the opening flap is located on the longer side of the envelope. The booklet envelope is an example of an open side envelope.
• Parallel Flap Envelope (aka Pocket Flap Envelope)
  This envelope has a square shaped flap, which parallels its opposite flat edge.
• Peel-n-Seal Envelope
  The peel-n-seal envelope is popular because you do not need to gum the flap close. A protective strip of plastic or paper covers a gum strip. Once you peel away the protective strip, you can seal the flap shut by pressing it onto the gum strip.
• Perforated Envelope
  This envelope is perforated (for easy tearing) either on the right or left wing. Used mostly for confidential documents such as bank statements.
• Pocket Envelope
  This envelope opens on the top or short side. Useful for putting in documents.
• Pointed Flap Envelope
  These envelopes are distinguished by the upper flap which is triangle-shaped. Most commonly used for greeting and invitation cards.
• Pointed Flap Folded Outside
  Similar to the pointed flap envelope except this envelope has its left and right wings folded on the outside instead on the inside.
• Regular Envelope
  This envelope is usually rectangle in shape and does not have a window.
• Self-Seal Adhesive Flap Envelope
  No need to seal with gum as you can apply water to the adhesive strip.
• Thumb Cut Envelope
  This envelope is designed without a flap. To open the envelope, one has to 'thumb' a u-shaped cut at the edge. This provides a secure way of transporting fragile documents.
• Triangle Flap Envelope
  These envelopes which are distinguished by the upper flap, left and rights wings are triangle-shaped.
• Wallet Envelope
  An envelope that has a long rectangular closure flap across the long edge of the envelope.
• Window Envelope
  Window envelopes are envelopes with a cut-out (called a window) to display the document's information. The window is covered with a transparent material like plastic to easily see essential information such as contact name and address.

2. What special features can custom/specialty envelopes offer?

• Additional cushion material
  Provides envelope contents with added protection.
• Eyelet envelope
  Useful for sending bulky documents as the string allows greater expansion.
• Self-seal adhesive flap envelope
  Used to seal flap without using water.
• Silicon adhesive flap envelope
  Seals flap with gum strip.
• Window envelope
  Useful for mass-mailed confidential documents where addresses and names need only to be changed.
• Wings are folded outside
  Used for automatic inserting machines.

3. What is the best way to store envelopes?

• Store them in a cool, dry and ventilated place.
• Store them in a sealed airtight container.