Direct Mail Formats – letter vs. self-mailer vs. postcard vs. booklet

Direct mail formats are too often decided by the personal preferences of the creative team. But the decision needs to be more strategic than that.  Let us show you how.   McCarthy & King Marketing provides strategically focused direct mail marketing programs for businesses and non-profits. 

Choosing a format – strategically

The direct mail format is the most visible part of your direct mail campaign.  It’s what everyone sees and wants to talk about. But choosing a format should be a strategic decision, not a personal preference.  You may have some idea of what you want for a format, but that choice should be determined by:

  • your marketing objective
  • the product or service you’re selling
  • your target audience
  • your follow-up plans
  • your budget

Direct Mail Format Options


The Lead Generation Letter Package

The Order Generation Letter Package

The Marketing Survey Package

The Direct Mail Postcard

The Folded Self-Mailer

The Self-Mailer Booklet (catalogs, newsletters, conference mailers)


The Retail Postcard

The Every Door Direct Mail Retail Flyer


The Fundraising Letter Package
donor acquisition and renewals)

Letter mailers vs. self mailers

It’s the classic direct mail question:  Which works better – a letter mailer or a self mailer?

Ready for the answer?  It depends.

Sorry, it’s just not that simple.  Let me explain:

Letter mailers have definite advantages.  Here are just some:

  • they look and feel personal
  • they are familiar to the reader
  • they allow you to include multiple inserts

But self-mailers also have advantages, including

  • they are graphically more interesting
  • they are not personal so they get shared more easily
  • they are cheaper to produce

If you already have a personal relationship with your target and you want to leverage that relationship, a personal letter works better than a self-mailer.

If you a promoting a community event, a self-mailer could be seen and read by multiple people in a household.

If you are selling a complex product or service that requires extensive explanation – and you are expecting a purchase, not a lead – a letter package with a longer letter and brochure is probably your choice.

If you are selling a product with tight profit margins and you need to keep your direct mail costs down, you will probably benefit from a self-mailer.

So you see … it depends

Letter mailers

Letter mailers could also be called envelope mailers because they all come in an envelope.  While a letter isn’t required, it is strongly (very strongly) recommended.  Why?  Because it serves as the reader’s guide to the mail piece.  It walks the reader through the message and tells the reader what he or she should do to take the next step.

At minimum, a letter mailer should include an envelope and a letter.  In the past, we would have also said it should also include a reply card or some type of order form.  Now most direct marketers are also using landing pages for response.  We still recommend reply cards as another option, but some marketers have move exclusively to landing pages for response.

We like landing pages too, but we also like giving people choices.  So almost all of our campaigns will include multiple response channels – including a landing page, a phone number and a reply card or form.  Even if you don’t expect many people to use the reply card, it serves as a visible and tangible reminder that you want them to respond.

Letter mailer sizes

Letter mailers are developed for multiple size envelopes, including:

  • #10 envelope – the standard business envelope.  Looks like real business mail.
  • 6×9 envelope – common for promotion mail – allow for more envelope artwork – larger size gets noticed.
  • 9×12 envelope – oversized mail – gets noticed, but you also pay more for postage
  • 6×11 envelope – popular because it’s the largest size before you move to higher postage
  • monarch size envelope – for invitations – has high curiosity level

Components of a letter mailer

So what goes into the envelope?  That depends on your product or service, and your objective.

Other than the envelope, your contents should include:

  • letter – this could be a simple one- or two-page letter for lead generation, or a longer letter for order generation
  • reply device – either a reply card or order form (with reply envelope)
  • brochure – optional, best for order generation – not normally recommended for lead generation
  • additional inserts as needed – (e.g, a testimonial sheet, a customer story, a premium sheet) – typically only for order generation (but could be worth testing in lead generation)


Self-mailers are any type of mailer that does NOT come in an envelope.  By eliminating the envelope, you are reducing costs (for both printing and mail inserting), but you must be sure all of the necessary elements can be incorporated into the mailer.

Self-mailer options

  • Postcard – the most popular of all self-mailers – comes in various sizes – smaller postcards (under 4.25×6 inches) get special postal discounts – larger postcards get more attention – 6×11 postcards give you the largest postcard without a postage surcharge.[break][break]
  • Folded Postcard – multi-panel postcard – most common is a 3-panel mailer (2 folds) but some can be 4, 5, 6 or more panels.  Most folded postcards also come with a built-in reply card.[break][break]
  • Booklet – best used for multi-product sales (catalogs) or sales requiring a longer sales pitch (like seminars or conferences)

Three-Dimensional Mailers

This is a very different format that could be either a letter mailer or a self-mailer.

Three-dimensional mailers are designed to get attention.  They could be a box, a tube, a bag, even a balloon.  They could be delivered by mail, by delivery service or in person.  They do get noticed.  People do open them and remember them.  But they are expensive.

You should only use them when you have a relatively small, well-define audience of otherwise difficult-to-reach prospects.


Get started or learn more

So what’s your next step?  If you’re close to making a move, we’d love to talk.  Call Bob McCarthy at 508-473-8643 or send him an email at

If you’re not there yet, let’s stay in touch.  Please join our mailing list and get all of our updates and articles.

Of course, if you have any questions, please don’t hesitate to call.

If you’d like to discuss an upcoming campaign – or if you’re looking for ways to improve an existing mailing program – call us and let’s schedule an introductory call.