Every SaaS founder has, at some point, paid for email volume they never used. Mailgun's "Foundation 50K" plan, SendGrid's "Pro 100K", Postmark's "Plus 50K" — the tiers are sized for the volume youthink you'll need three months from now, not what you're actually sending today. So you overbuy, write off the unused emails, and pretend the monthly cost is just "infrastructure overhead."
This is a holdover from an era when SaaS revenue was predictable enough that you could forecast volume and lock in a tier. Modern SaaS isn't that predictable, and the pricing model needs to catch up. This post is the argument for pay-as-you-go email infrastructure, with concrete numbers showing why seat-based plans cost most teams more than they realize.
How seat-based pricing actually works (and why it bites)
The standard email-platform tier looks like this:
- $15/month for 10K emails
- $35/month for 50K
- $80/month for 200K
- $300/month for 1M
The economic logic from the vendor side: bundle the per-message cost with a commitment, lock revenue, smooth out the bandwidth cost across a tier. From the customer side: you're paying a fixed price for a ceiling.
The problem: SaaS volume isn't a smooth curve. It's spiky. You ship a feature that triggers a 3x increase in welcome emails for two weeks. You run a re-engagement campaign that doubles your monthly volume for one cycle. You go viral on a Tuesday. Then the spike subsides and you sit at half your tier again for three weeks.
On a monthly tier you pay the spike OR you pay the ceiling. Either way, you're eating loss.
The math: what teams actually pay
We crunched the numbers on the seat-based plans of the major incumbents at 100K monthly sends — a typical mid-stage SaaS volume:
| Provider | Plan name | Monthly $ | Effective $/1K |
|---|---|---|---|
| SendGrid | Pro 100K | $89.95 | $0.90 |
| Mailgun | Foundation 100K | $80 | $0.80 |
| Postmark | Plus 50K + overage | $50 + $1.25/1K * 50K = $112.50 | $1.13 |
| Mailjet | Premium 100K | $58.95 | $0.59 |
Now consider the team that actually sends 100K. Half the months they're at 100K. The other half they're at 60K — but they paid for 100K. Their effective rate becomes $0.90 / 0.6 = $1.50 per 1K on the slower months. Across a year that's real money — typically $300-$600 of unused volume per year for a single team on a mid-tier plan.
Multiply by every team in a multi-product company and you're into low five-figure waste annually.
What pay-as-you-go actually means
True pay-as-you-go (sometimes called "usage-based" in pricing circles) means you're billed for what you sent, period. No commitment, no ceiling, no overage shock. The unit price is constant or volume-discounted.
Sendr365's pricing is structured this way. Free tier of 100 emails/month, no card required. Above that, you pay per 1,000 sent at a transparent rate that drops as volume rises. The rate is the same whether you send 5,000 or 500,000 in a given month — no "you broke into the next tier" surprise.
Concretely: 100K sends costs ~$60 on Sendr365 versus the seat-based equivalents above, AND if you only sent 60K that month you pay for 60K. The difference compounds over a year.
Why pay-as-you-go fits SaaS economics specifically
1. SaaS volume is correlated with revenue, not predictable
When you onboard a 50-person team in week 3, your transactional volume spikes instantly: invitation emails, welcome flows, notifications. Your revenue also spiked — that contract is paying for the volume. Pay-as-you-go aligns the cost with the revenue automatically. Seat-based pricing makes you pre-commit before the contract closes and write off the unused capacity if it doesn't.
2. Burst sends are the norm, not the exception
Re-engagement campaigns, Black Friday blasts, security incident notifications, product launches — these are real, recurring SaaS workloads. They burst 5-10x baseline. On seat-based pricing, you either commit to the burst tier (and overpay all year) or you exceed the tier and eat overage charges that are usually 2-3x the regular rate.
3. Team-scale pricing penalizes early-stage SaaS
Most seat-based plans have minimum tiers ($15-$30 / month). For a pre-revenue team sending 200 magic links a month, that's a $0.075-per-email effective rate — completely irrational economics. Pay-as-you-go with a free tier means you scale your spend with your business, not with your vendor's minimum commitment.
4. Crypto and global teams
Seat-based plans usually require a credit card. For founders in markets where SaaS card adoption is patchy (large parts of Asia, Africa, LatAm), this is a genuine blocker. Pay-as-you-go with crypto billing — what Sendr365 ships — gets rid of that gate. You fund your account in BTC, ETH, USDT, or any major stablecoin and burn through the balance as you send.
The objections (and the rebuttals)
"Pay-as-you-go is unpredictable"
It's as predictable as your sends, which are as predictable as your product usage. If you have analytics on your DAU, you have analytics on your email volume. Forecast monthly cost the same way you forecast Stripe fees: a function of usage. That's easier than guessing tier-bracket commitments.
"What if we get DDoS'd / spammed / our auth flow breaks"
Real risk on any model. Solve it with rate limits at the application layer (which you should have anyway) and per-tenant send caps at the platform layer (which Sendr365 enforces by default). The risk is identical on a seat-based plan; you just hit the cap differently.
"We need budget predictability for finance"
Set a monthly cap on your account; we'll alert before you cross it. Many teams cap at 1.5x their three-month rolling average and adjust quarterly. That gives finance their number while keeping the upside if revenue grows.
What to look for when evaluating pay-as-you-go email vendors
- Transparent unit pricing. Per-1K rate, no hidden tiers, no "contact sales" for high volume.
- Free tier. 100-1000 emails/month free is enough to evaluate without a card.
- No monthly minimums. If you send 50, you pay for 50 (or zero if you're inside the free tier).
- Real-time usage dashboard. Knowing what you've spent this month before the bill arrives.
- Hard caps and alerts. Spend protection if your code gets into a loop.
- Same deliverability as seat-based. Unit price doesn't dictate inbox placement; the platform's reputation does. Don't trade deliverability for cost.
What we built
Sendr365's pricing is the answer to the math above:
- Free for the first 100 emails / month, every account.
- Transparent per-1K rates that drop with volume — published openly on the pricing page.
- No card required to sign up. Crypto-funded accounts available from the start.
- Hard caps + budget alerts wired into every account.
- Same deliverability infrastructure (DKIM, IP pools, complaint handling) as seat-based competitors.
For most SaaS teams sending 10K-500K/month, the savings versus a seat-based plan are 30-50% without giving up any deliverability. For teams above 1M sends/month, volume discounts kick in that match or beat enterprise contracts from the incumbents — without the contract.
If you're currently on a seat-based plan and feel the friction, try Sendr365 free for a month and compare the bill. The math usually speaks for itself.