Busy business folks and consumers who receive a lot of mail develop a cold-eyed routine for dealing with stacks of unopened envelopes. Promotional items can dramatically increase your odds of breaking through that sort of "don't bother me" barrier.  Pairing a sales letter with an imprinted gift raises response rates because it brings recipients' emotions into play.  Here's how:

* Curiosity.  A recipient who can tell that an envelope contains some unknown item has a harder time throwing away the envelope without opening it.  "What IS that thing inside the envelope?" he or she wonders, and sticks a thumb under the flap to tear it open and see.  If you're enclosing a flat item like a magnet, you can stimulate curiosity through the teaser copy on the envelope, such as "Enclosed:  a powerful attractor that reveals the secret of low-priced office supplies."

* Gratitude.  According to psychologists, giving something away that people value creates a sense of obligation in recipients.  Someone opening a package to find a mouse pad that they immediately put into use feels well-disposed toward the firm whose name and Web site are on it.

* Memory.  Someone who suddenly needs a printing company or a hotel reservation is more likely to call the printer whose calendar hangs on his wall or the hotel whose pen she's been using for weeks than another establishment whose name and number he would have to look up.  Direct mail gets that memory jogger -- your imprinted item -- into their office in the first place.

* Suspense.  A series of mailings, each with a related item, can get the later packets in the sequence eagerly opened.  For instance, you can send a pen and pen holder, or coaster and mug, or checkers pieces and board separately for greater impact.  In this sort of campaign, the accompanying letters drive home your thematic message exemplified by the imprinted items you've chosen.

Some warnings are in order, though, to make sure enclosing promotional products in direct mail doesn't backfire.

* Check with postal officials before finalizing your plans.  With automated processing, you'll need to make sure your mailing won't rip apart in postal machines.  A pen or keychain might require a padded envelope to arrive intact at the other end.

* Consider the circumstances of recipients when sending odd-sized mail. An envelope or package that doesn't fit through a mail slot can force someone to make a special trip to the post office to pick up the item. This applies mainly to consumers and smaller businesses.

* Remember that the relevant indicator of success in direct mail is profitability, not percentage of response.  If your goal is inspiring strategic alliances or selling $10,000 cruises, even one "hit" out of a thousand makes the mailing a profitable endeavor.

* With parcels, steer clear of a "home-made" look with hand-addressing, stamps and no return address.  You could become a national laughingstock if a recipient misunderstands your intent and summons the bomb squad!

* As with any use of promotional products, make sure that the item you choose will be welcomed by your target market, that the item will work and last and that the imprinting is professionally done.