Direct Mail vs Email ROAS
Email is the default channel for Shopify re-engagement. Direct mail is the physical alternative. This comparison breaks down when each delivers better returns — and how the two work together.
The cost structure is fundamentally different
Email has near-zero marginal cost per send. Adding 10,000 recipients to an email campaign costs almost nothing beyond the platform fee. Direct mail has a real per-piece cost — print, postage, and platform fees per postcard. This shapes how each channel is best used.
Because email is so cheap to send, it works at scale and low conversion rates are acceptable. Because direct mail has a per-piece cost, it needs to be targeted at audiences with meaningful conversion potential — and the ROAS needs to be calculated against the actual postcard cost per piece, not just revenue.
Where direct mail typically outperforms email
Lapsed customers with low email engagement
If a customer hasn't opened your emails in 90 days, the email win-back sequence has already failed. Their inbox filters your domain as low-priority. A postcard arrives via a completely different channel — one they haven't exhausted. ROAS on this segment is often higher for direct mail than the marginal email sends.
High-LTV segments with premium positioning
A physical postcard communicates care and quality that email cannot match. For brands with a strong brand identity or high average order value, the physical format reinforces brand premium in a way that an inbox message doesn't.
Competitive inbox environments
In categories where customers are on many brand mailing lists (fashion, beauty, homewares), email open rates are low across the board. The letterbox is far less competitive. Standing out in the letterbox is easier than standing out in an inbox.
Low digital touchpoints by nature
Some customer segments — particularly older demographics or customers in lower-digital-engagement areas — have lower email open rates by disposition. These segments often respond better to physical mail.
Where email typically outperforms direct mail
- High-frequency, low-margin sends — Promotional broadcasts to your entire list where per-piece cost would make direct mail uneconomical
- Time-sensitive campaigns — Flash sales, 24-hour offers, or event-based sends where the 3–7 day postal delivery window is too slow
- New subscriber onboarding — Welcome sequences for new subscribers who haven't purchased yet (no physical address collected)
- Content marketing and education — Newsletter-style content that requires dynamic, hyperlinked content
The complementary channel model
The highest-performing approach for most DTC brands isn't email vs. direct mail — it's email then direct mail. A common sequence:
- Email sequence runs first (low cost, immediate)
- Customers who convert via email are suppressed from the postcard send
- Customers who didn't respond to email receive the postcard (higher cost, different channel)
- Overall campaign ROAS is calculated across both channels combined
This approach preserves email's low-cost advantage for easy conversions while deploying direct mail's higher-cost, higher-cut-through format only for the customers who need the additional channel.
Calculating combined campaign ROAS
When running email and direct mail together as a coordinated sequence, the total campaign ROAS is:
In practice, the marginal email cost is often low enough that it barely affects the combined ROAS figure, making the postcard ROAS the dominant variable to optimise.
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