The short answer
Per-user (per-mailbox) pricing charges for every address you protect. Per-domain pricing charges once for the domain, however many mailboxes it has. For a domain with more than a handful of mailboxes, per-domain is usually cheaper and much easier to budget. For one to three mailboxes, a per-user plan can cost less.
The prices we're comparing
iBlockSpam (real, beta pricing, USD excl. tax):
- Protect: $12 per domain/month billed annually ($144/year), or $15 month-to-month.
- Protect Plus: $19 per domain/month billed annually ($228/year), or $24 month-to-month.
Hypothetical competitor: "$3 per mailbox/month". This is an illustrative figure, not any specific vendor's price. Substitute the real quote you have.
Break-even points
The break-even is the plan price divided by $3.
| iBlockSpam plan | Price per domain/month | Break-even vs $3/mailbox | Per-domain is cheaper from |
|---|---|---|---|
| Protect, annual | $12 | 4 mailboxes | 5 mailboxes |
| Protect, monthly | $15 | 5 mailboxes | 6 mailboxes |
| Protect Plus, annual | $19 | 6.33 mailboxes | 7 mailboxes |
| Protect Plus, monthly | $24 | 8 mailboxes | 9 mailboxes |
At exactly the break-even number, the two cost the same.
Worked examples
Example 1: a 3-person firm
- Hypothetical per-user: 3 × $3 = $9/month
- Protect, annual: $12/month
Per-user is $3/month cheaper here. If the firm expects to hire, or uses shared addresses that need their own mailboxes, that changes quickly.
Example 2: a 12-person office
- Hypothetical per-user: 12 × $3 = $36/month ($432/year)
- Protect, annual: $12/month ($144/year)
- Protect Plus, annual: $19/month ($228/year)
Protect saves $288 a year compared with the hypothetical plan. Protect Plus, which adds daily monitoring, a monthly owner report and a human setup session, still saves $204.
Example 3: 40 mailboxes, month-to-month
- Hypothetical per-user: 40 × $3 = $120/month
- Protect, monthly: $15/month
- Protect Plus, monthly: $24/month
Example 4: one business, three domains
A business with a main domain (25 mailboxes), a second brand (5 mailboxes) and a legacy domain kept for old addresses (2 mailboxes):
| Domain | Mailboxes | Hypothetical $3/mailbox | Protect, annual |
|---|---|---|---|
| main | 25 | $75 | $12 |
| brand | 5 | $15 | $12 |
| legacy | 2 | $6 | $12 |
| Total/month | 32 | $96 | $36 |
Per-domain pricing is per domain, so each separate domain is a separate subscription. If the legacy domain only exists to forward mail to the main one, check whether it can be set up as a domain alias instead; domain aliases are unlimited and don't need their own plan.
Things a per-mailbox quote often hides
- Shared mailboxes and role addresses. info@, sales@ and accounts@ may count as billable mailboxes. With per-domain pricing they don't change the price.
- Staff turnover. Leavers' mailboxes are often kept for a while. Per-user plans keep charging for them.
- Growth. Every hire is a billing change and sometimes a purchase approval.
- Minimums. Some per-user plans set a minimum seat count, which moves the break-even.
What per-domain doesn't mean
Unlimited mailboxes means no limit on mailbox count, not unlimited mail. Each domain includes:
| Included per domain | Amount |
|---|---|
| Inbound messages | 100,000 per month |
| Maximum inbound message size | 400 MB |
| Outbound relay messages | 500 per month |
| Outage spooling | Up to 5 days |
| Message history | 30 days |
For most domains, 100,000 inbound messages a month is a lot of headroom. A high-volume domain should check its current traffic before choosing any plan.
Price is not the whole decision
Compare what's included, not just the number. Check where mail is processed (ours is processed in the United States), how quarantine works for users, whether outages are covered and how you leave. See features, security, why businesses choose iBlockSpam and how to switch filters safely.
Managing many domains for clients? Partner terms, including pricing, are agreed individually; see partners and the MSP page. To work out your own cost to serve each client domain, see the MSP spam filter pricing guide.
Frequently asked questions
When is per-user pricing cheaper?
When you have very few mailboxes on a domain. Against a hypothetical $3 per mailbox/month, Protect billed annually breaks even at 4 mailboxes and Protect month-to-month at 5. Below that, per-user pricing costs less. Above it, per-domain pricing costs less, and the gap grows with every new mailbox.
Does unlimited mailboxes mean unlimited email?
No. Unlimited refers to the number of mailboxes on a domain. Each domain includes 100,000 inbound messages per month, a 400 MB maximum inbound message size and 500 outbound relay messages per month. Check your current volume if your domain is unusually busy.
Do aliases and shared mailboxes cost extra?
No. Domain aliases are unlimited, and because pricing is per domain, shared mailboxes and addresses like info@ or accounts@ don't add to your bill.
Are these prices final?
They are beta pricing in USD, excluding tax. If a price changes, existing subscribers get at least 30 days' notice by email, and the new price applies only from the first renewal after that notice. See our terms.
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