Email & SMS: From Channel Cost to Profit Contribution

ESP and SMS fees are small until you add discounts and list fatigue. Measure profit contribution, not opens.

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Owned channels look free and are not. Platform fees, discount codes, deliverability work, and unsubscribes all hit true net profit—flows deserve ranking by contribution, not open rate.

The "free channel" myth

ESP and SMS platform fees scale with list size and send volume, and every discount code sent to a list erodes margin on each redemption—none of that shows up in an open-rate report.

Costs that compound over time

Deliverability consulting, list cleaning, unsubscribe and spam-complaint management, and the opportunity cost of fatigue-driven unsubscribes reducing future revenue from the list.

Measuring by contribution, not opens

Rank flows and campaigns by profit contribution per send, factoring in discount cost explicitly, rather than by open or click rate alone.

FAQ

Do discount codes in email always hurt profit?

Not if they are targeted—win-back flows, for example—rather than blanket sitewide discounts. Model the incremental margin, not just the incremental revenue.

Should SMS get the same profit scrutiny as email?

Yes, and often more—per-message SMS platform fees make low-margin blasts costlier per contact than the equivalent email send.

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CostRadar tracks ESP and SMS platform fees alongside discount cost, so owned channels get ranked by profit contribution instead of engagement metrics alone.