Why the lowest-cost follow-up isn't always the most profitable and how to decide when another mailing is worth the investment.
A direct mail campaign goes out. Responses begin coming in. But what about the people who don't respond?
For many marketers, the next step seems obvious: send an email. It's fast, inexpensive and doesn't require another investment in printing and postage.
But is it actually the more economical choice?
The least expensive message to send isn't necessarily the most cost-effective message for generating a response.
For marketers in fundraising, healthcare, insurance, and financial services, where decisions often require consideration, trust, and timing, the economics of a second touch deserve a closer look.
Email generally costs less to send, but a second direct mailing can be more profitable when it generates enough additional conversions to justify its higher cost. The best follow-up channel depends on audience accessibility, incremental response, customer value, and total campaign expense.
Rather than choosing a channel based solely on cost per contact, marketers should compare cost per incremental acquisition and net incremental contribution.
That requires looking beyond the initial response to understand how long a message continues working, how much attention it receives, and whether another touch creates measurable value.
Email has a significant advantage over direct mail: distribution costs are low. Once a marketer has an established email platform, a usable contact list and the necessary creative, sending another message may cost relatively little.
But sending a message and earning someone's attention are two different things.
An email must reach the inbox, compete with other messages, earn an open, and communicate its value before the recipient moves on.
Direct mail faces its own challenges. Not every delivered piece is read, and not every person who reads an offer will respond. However, physical mail offers something different: a chance to stay visible beyond the initial interaction.
A postcard might sit on a counter. A fundraising appeal might remain with the household's bills. An insurance offer might be set aside for a spouse to review.
That staying power can create additional engagement opportunities without requiring another paid communication.
Research from JICMAIL, the UK's independent mail audience measurement organization, shows that physical mail can stay active long after delivery.
These measurements describe different aspects of engagement. Lifespan measures how long a piece remains in the household. Interactions reflect repeated engagement with the item. Attention time represents cumulative exposure, not one uninterrupted reading session.
Together, they show why you shouldn't evaluate a direct mail piece solely on the day it arrives.
The same JICMAIL study found that 9.5% of mail items prompted a website visit, reinforcing the relationship between physical mail and digital engagement.
Email engagement is measured differently.
Litmus, an email analytics provider, classifies email engagement by how long a message stays open.
These classifications do not establish that the average email is viewed for only two to five seconds. They also cannot be directly compared with JICMAIL's cumulative attention measurements.
But they illustrate an important consideration: marketers need to distinguish between delivering a message and earning meaningful engagement.
Direct mail's potential advantage isn't simply that someone sees it once. The same piece can create repeated opportunities for attention over several days.
For products and services that require consideration, that difference may be valuable.
Consider a hypothetical acquisition campaign with 20,000 eligible nonresponders.
The marketer has two follow-up options: send an email or produce a second direct mail package.
For this example, assume each incremental conversion contributes $250 after applicable variable costs, before follow-up marketing expenses.
At first glance, email has a considerable advantage. It requires only four incremental conversions to recover its cost, compared with 68 for direct mail.
But breaking even isn't the same as maximizing profit.
Suppose the email generates 20 incremental conversions while the second mailing generates 100.
Email produces a substantially higher percentage return on the marketing investment.
But direct mail generates twice as much net incremental contribution.
That distinction matters.
A marketer focused exclusively on ROI percentages might choose email. A marketer focused on maximizing profitable acquisition might reach a different conclusion.
Neither channel is automatically the better choice. The answer depends on the actual incremental response each can generate.
This is one of the most useful calculations for marketers considering a second mailing.
In our example, direct mail costs $16,000 more than email.
At a $250 contribution per conversion, the additional investment requires 64 more incremental conversions to break even with email.
Incremental conversions required = Additional channel cost ÷ Contribution per conversion
$16,000 ÷ $250 = 64 additional conversions
If email generates 20 incremental conversions, direct mail needs more than 84 incremental conversions to produce greater net contribution.
The question is no longer whether direct mail costs more. We already know it does.
The question is whether the additional investment can produce enough incremental conversions to justify the difference.
And that is something marketers can test.
The economics of follow-up apply across industries, but why people respond, or don't, can vary widely.
A donor may receive an appeal, intend to contribute, and then become distracted by other priorities.
A second communication can remind them, reinforce the organization's mission, or introduce a new reason to give.
For fundraising organizations, the calculation should consider more than the immediate donation. Donor retention, subsequent giving, and long-term donor value may influence how much an organization can reasonably invest in reengagement.
However, include future contributions in ROI calculations only when supported by realistic donor-value assumptions.
Healthcare decisions often involve scheduling, cost, family responsibilities, and personal considerations.
Someone who doesn't respond to an appointment reminder or screening invitation may not be uninterested. The timing simply may not have been right.
A follow-up campaign could use email for convenience and speed, or physical mail when the communication benefits from a tangible reminder patients can retain.
The appropriate approach also depends on patient communication preferences, consent, privacy requirements, and the nature of the service being promoted.
Insurance decisions frequently require consumers to evaluate coverage, compare costs and understand benefits before taking action.
This is particularly relevant to affinity programs, where offers may be distributed through associations, employers, or other membership relationships.
A second communication might reinforce a benefit, answer a common question or remind eligible members of an enrollment opportunity.
Email may be efficient when permissioned addresses are available. But an organization with access to a postal membership list may not have equivalent access to member email addresses.
In that situation, the channel decision isn't simply about cost. It's about the ability to reach the intended audience.
Banks, credit unions, and other financial institutions face similar challenges.
Consumers may need time to consider a loan, evaluate a credit card offer, or understand the benefits of opening a new account.
A second communication can reinforce the original offer, explain a benefit more clearly, or simplify the next step.
For financial services marketers, follow-up strategies must also account for applicable advertising, privacy, consent, and disclosure requirements.
Even when a second mailing makes financial sense, marketers face another decision: Should they repeat the original package or invest in something new?
Repeating a proven package isn't necessarily a bad decision. If the initial creative performed well, the second mailing may simply reach recipients at a better time.
On the other hand, changing the message could help overcome an objection or communicate a benefit that wasn't emphasized initially.
The decision should be economic, not merely creative.
For example, if modifying the second package adds $1,500 in creative and production costs, and each incremental conversion contributes $250, the revised creative needs six additional conversions to recover that investment.
Whether it actually produces those conversions is a question for testing.
Potentially, yes.
Planning both waves during the original production cycle can create efficiencies through shared materials, consolidated print runs, and reduced setup costs.
However, printing both waves upfront also creates inventory and response-management considerations.
A marketer who prints the entire second-wave quantity before measuring first-wave responses may end up with unnecessary inventory.
An alternative is to print common materials together while delaying personalization and final mail preparation until you establish the second-wave audience.
That lets you suppress responders and adjust mailing quantities.
The best approach depends on the package format, printing method, personalization requirements, and expected mailing quantities.
Sometimes the best follow-up isn't another mailing.
A coordinated campaign might use physical mail to introduce an offer and email to provide a convenient reminder or direct response opportunity.
Alternatively, email could serve as the first follow-up, with a second physical mailing reserved for selected nonresponders.
The objective isn't to increase touches indiscriminately. It's to determine which sequence produces the greatest incremental value.
Because direct mail can sit in the home for days, marketers should also consider that the original piece may still be influencing decisions when subsequent communications arrive.
This creates an attribution challenge.
A customer who responds after receiving an email may have been influenced by the original mailing, the email, or both.
Assigning the conversion to the last channel touched doesn't necessarily reveal which communication created the incremental response.
The most reliable way to evaluate follow-up channels is through controlled testing.
For a campaign with a sufficiently large audience, randomly divide eligible nonresponders into four groups.
For the most reliable comparison, groups should be comparable, offers consistent, and the measurement window clearly defined.
Where possible, random assignment should occur among contacts eligible to receive both channels. Otherwise, differences in email availability or consent may distort the results.
The no-contact group is especially important because some people will convert even without another communication.
Without a control group, marketers risk attributing conversions to the follow-up that would have happened anyway.
A second mailing doesn't need the highest percentage ROI to be the most profitable option.
Likewise, email doesn't need to generate the same number of conversions as direct mail to be a worthwhile investment.
The right decision depends on the value created relative to the cost.
Email generally costs less per message sent. However, it isn't necessarily the least expensive channel per incremental customer acquired. That depends on response rates, audience accessibility, conversion value, and total campaign expenses.
Research shows direct mail can stay in households for several days and generate repeated interactions. JICMAIL's Q2 2026 findings report an average lifespan of 7.4 days and 151 seconds of cumulative attention per direct mail item. However, email and physical mail attention are measured differently, so you shouldn't treat these figures as a direct comparison.
Not necessarily. Repeating a proven package can reduce costs, while a new message may give recipients another reason to respond. The best approach depends on whether the revised creative generates enough incremental conversions to justify its additional expense.
There is no universal interval. The appropriate timing depends on the offer, response window, decision cycle, and campaign objectives. Marketers should allow sufficient time to measure first-wave responses and suppress responders before preparing the second mailing.
Yes. Email can reinforce a physical mailing, provide a convenient response path, or serve as an inexpensive first follow-up. Evaluate coordinated campaigns based on incremental conversions rather than assigning all credit to the final communication.
Calculate the follow-up's incremental contribution, subtract all associated campaign expenses, and divide the result by those expenses. When possible, use a randomized control group to distinguish conversions caused by the follow-up from those that would have occurred anyway.
Email will generally have a lower distribution cost than physical mail. That makes it an attractive follow-up channel, especially when marketers have reliable contact information and need to communicate quickly.
But low distribution cost isn't the same as low acquisition cost.
Direct mail offers a different kind of engagement. Its physical presence, potential for repeated interactions, and ability to remain in the household can give an offer more opportunities to be considered.
That doesn't mean every campaign needs a second mailing. Nor does it mean email should be replaced.
It means marketers should evaluate the second touch based on the incremental value it generates, not the cost of sending it.
The smartest follow-up strategy isn't necessarily the cheapest message. It's the one that produces the greatest profitable response.
And sometimes, that means mailing again.
Industry research
Financial methodology
All financial examples are hypothetical calculations developed to illustrate break-even economics, incremental contribution, and marketing ROI. They are not actual Streamworks client results or published industry averages. The calculations assume equal eligible audience sizes, fixed campaign expenses, and a consistent $250 contribution per incremental conversion. Real-world campaign results will vary.