Direct marketing and direct mail were once synonymous. Then e-mail arrived, and B2B marketers abandoned direct mail in droves. Now e-mail has fallen out of favor (at least for acquisition), but many companies are unwilling to pay what is now regarded as the "high cost" of direct mail. That void has been filled by the emergence of new online vehicles such as paid search and content syndication.

One of the keys to any successful demand generation strategy is balance. We find our most successful clients are those that strive to balance "push" campaigns like e-mail and direct mail with "pull" campaigns such as content syndication and paid search.

One clear advantage of "push" campaigns is you can pre-select your audience via the list process. Cost per lead may be higher, but a greater percentage of inquiries are likely to meet your basic demographic criteria.

"Pull" campaigns rely on the reader's initiative to take action. And though you can target a particular audience through a well-honed media strategy (and even creative to some extent), you have less control over who responds, by default. Cost per lead is typically much less than even e-mail, but a higher percentage of the leads is likely to be off-target.

Another key difference between push and pull campaigns is timing. If your e-mail, no matter how effective, arrives in someone's inbox and that individual only recognizes the need for your product a month later, chances are he or she won't respond.

Conversely, the nature of "pull" campaigns is that they're always "on", so regardless of when your prospect realizes the relevant need, or reaches the level of pain relative to a particular business or technical problem that he or she starts to research or investigate solutions, you'll be in the right place at the right time.

That's why pull campaigns can be particularly effective for established or mature product categories, when the marketing challenge is less about building demand and more about simply capturing those prospects who are "shopping" for your type of solution.

Push campaigns, on the other hand, are ideal for more nascent categories for which some degree of education is required about why the prospect would need your solution in the first place. For most companies, the ideal is a balance of the two.