Why Delivery Volume is a Great Target Metric for Email & SMS Campaigns

When we think about campaign planning each month, we like using message delivery volume as a target metric.

Most teams default to counting campaigns per month or week, rather than the actual number of deliveries. We prefer to invert that: start with a target delivery count, then back out how many campaigns and which segments you need to hit it.

The goal is to predictably match and exceed previous campaign revenue each month (adjusted for seasonality, inventory, and other real-world constraints).

The core idea:

Revenue = Revenue per delivery × Volume of deliveries

With a fairly stable revenue-per-delivery ratio, your main lever is volume. You can apply this at the account level, by channel (email vs. SMS), or—ideally—by segment and message theme. A planning snapshot might look like this:

For email and SMS, you generally need to hit a volume baseline to produce results in the same ballpark as the prior month. If you fall far short on deliveries, conversion rates have to work disproportionately hard to close the gap.

For example: if last month you had 400,000 campaign deliveries and this month you only reach 200,000, then just to stay even on campaign revenue you would need roughly double the sales conversion rate (or AOV). Improving conversion over time is realistic; doubling it across the entire campaign mix in one month usually is not—and even then you have only broken even.

Planning around delivery volume keeps campaign frequency and reach aligned with revenue goals. A side benefit: you can forecast ESP costs more cleanly, since pricing is often tied to sends— especially for SMS/MMS, where cost per message is higher than email.

Diminishing marginal returns per delivery

When metrics are trending well, you can often increase delivery volume. Eventually you hit diminishing returns: each incremental send contributes less revenue. That is the signal to slow volume growth and re-evaluate.

A ratio view highlights falling revenue effectiveness as volume ramps:

At that point, pushing volume alone—via bigger segments or higher frequency—yields smaller gains. It often makes more sense to hold deliveries steadier and improve conversion through creative, segmentation, and testing on the same core campaigns and flows.

If you have history, plot deliveries vs. revenue. Months where higher deliveries track with higher revenue suggest you may still be below an efficient volume range. If revenue flattens while deliveries climb, you are likely at or past that range.

Adjust for list attrition and seasonality (covered below) before drawing hard conclusions from a single chart.

Backing into a campaign delivery target

If you are not yet past optimal volumes, one starting formula:

Campaign delivery target ≈ List size × Number of campaigns × 45%

The percentage is a rough stand-in for the average share of your full list that receives a given campaign. Your number will vary with how aggressively you segment. A common pattern layers engagement tiers, for example:

• Highly engaged: receives 100% of campaigns
• Medium engaged: receives about 50% of campaigns
• Low engaged: receives under 25% of campaigns

Combine those delivery assumptions with a theme-based calendar and you get a concrete monthly plan: themes, segments, and send counts that roll up to a volume target.

List attrition

Lists shrink naturally through unsubscribes, bounces, and complaints. The objective is sustained net-positive list growth after attrition—not unlimited blasting.

As delivery volume rises, attrition can accelerate. If acquisition does not keep pace, net growth can slip negative, which erodes future campaign reach.

A practical benchmark to aim for is on the order of 7% net list growth per month. With annual attrition often above 20% (roughly 2% per month), that implies a meaningful gross acquisition rate— often approaching ~10% gross monthly adds depending on your baseline churn. Sustained net growth under about 3% can mean you are not staying ahead of stagnating subscribers who have not yet unsubscribed.

Seasonality

Low season

For highly seasonal products, scale delivery targets down in quiet periods. Think maintenance frequency: keep the list warm (which supports deliverability in peak season), protect churn, and hold a steady low-season revenue contribution from email/SMS.

Low-season success metrics often include:

• Open and click rates stable at a reasonable absolute level
• Unsubscribe rates controlled; net list growth positive or at least neutral
• Email/SMS holding a steady share of monthly revenue; upside comes from efficiency and flows more than big volume spikes

Low season is also a strong window to tighten flows and segmentation on paths like visitor → lead → first purchase → repeat—efficiency gains compound when high season returns.

High season

Demand and traffic rise; acquisition spend often does too. Email and SMS delivery volumes should generally increase with higher campaign frequency and the natural lift in automated flow volume. Depending on how seasonal you are, planned campaign deliveries might be multiples of an off-month.

You may even tolerate slightly negative net list growth for a window if it maximizes peak-season revenue—provided you understand the tradeoff and recover list health afterward.

Many teams use a seasonality index as a month-to-month multiplier on an ideal delivery target so planning stays consistent year-round.

Campaign vs. flow volumes

So far the emphasis has been on campaigns, which usually drive most of total delivery volume and swing the most when you change segments or cadence. Flows follow the same principle: you can plan and tune them toward healthy volume targets.

Flow volume is usually steadier than campaigns, but it moves when you:

• Launch or retire entire flows
• Add or remove touchpoints
• See list or site traffic grow or shrink
• Change filters or trigger logic

Treat each flow message as a discrete send alongside campaigns. Flows often earn higher revenue per delivery; if a touchpoint underperforms your best campaigns, consider cutting or refreshing it so subscribers see stronger campaign creative instead.

Flows also show diminishing returns—later steps tend to contribute less, for example in a welcome series:

When a flow keeps outperforming campaigns, consider more touchpoints or relaxed entry filters to grow qualified volume. When planning the month, account for flow deliveries first, then layer campaign volume—so you do not accidentally starve automations after campaigns consume your effective bandwidth.

Side note: standout evergreen campaigns can be recycled into flows so new subscribers see proven creative—often lifting revenue per delivery for those automated touches.

Summary

Delivery volume is a practical anchor for email and SMS planning. Setting explicit monthly targets helps you align cadence, segmentation, and revenue goals—and forecast cost as channels scale. We recommend baking delivery volume into your content calendar process alongside themes and segments.