The size and shape of the flaps and type of seams combine to form six main types of envelopes used for the bulk of non-specialty applications.
- A-Style or Announcement Envelopes
Open side envelopes with square, often deep flaps and side seams, these envelopes - also called A-Style or A-Line -- can have deckle edges on the top flap and are often used with matching text and cover papers in white and colors. Typical uses of this style are for greeting cards, announcements, informal invitations, and small booklets.
- Baronial Envelopes
Used for formal invitations and announcements, greeting cards, and distinctive social stationery, this style is an open side, almost square envelope with pointed flaps and diagonal seams. Inner/Outer envelope sets come with the (slightly smaller) inner envelope ungummed.
- Booklet Envelopes
Open side envelopes with small square or wallet flaps and side seams, these envelopes are ideal for overall printing and mailing. Booklet envelopes are used not only for booklets but for brochures, catalogs, annual reports and other multi-page mailings. They work well with automatic insertion machines.
- Catalog Envelopes
Usually open end envelopes with wallet style flaps and center seams, catalog envelopes are used for mailing magazines, folders, reports, catalogs, and other heavy-weight materials. Policy envelopes, used for insurance policies, wills, mortgages, and other legal papers sometimes come with a full-view window on the face.
- Commercial Envelopes
Used for business, direct-mail, and personal correspondence and direct-mail style envelopes, this style includes the standard #10 envelope. Also called business, standard, or officials, these are open side envelopes usually with commercial style flaps and diagonal seams although some sizes come with side seams and square or pointed flaps. The Monarch is a variation of the #7 ¾ envelope but with pointed flap. The window version has single or double windows that allow addresses to show through the face of the envelope. They are normally used for invoices or billing statements, paychecks and receipts.
- Square Envelopes
With their large square flaps and side seams, square envelopes are distinctive but the nonstandard size and shape can increase postage costs. These are used primarily with announcements, advertising, and specialty greeting cards or other mailings where the sender wants to draw attention to the contents.
Specialized envelope styles and sizes are based on these common styles.