"Unlimited mailboxes" is the promise Smartlead and Instantly share, so it is not enough to choose. What changes is what each vendor bills around that promise: sends, contacts, data credits, client workspaces, dedicated servers. This article compares the two using their official pages, Smartlead and Instantly, and their pricing pages, Smartlead and Instantly, consulted on September 29, 2026.
Ember is not a bulk sending tool and does not replace either. We describe these two tools from their own pages; their offers and prices change, so check them before deciding. All prices are in US dollars.
What the two tools have in common
- Unlimited connected mailboxes. Smartlead writes: "Add unlimited mailboxes and store unlimited leads". Instantly's page announces unlimited email accounts on its sending plans.
- Mailbox warm-up. Smartlead announces automatic DNS setup, warm-up and sender rotation; Instantly announces unlimited email warm-up on its sending plans. Check Smartlead's pricing page for what each plan includes.
- A contact database. Instantly highlights a database of 450M+ B2B leads; Smartlead displays verified-email quotas per plan, from 2,000 to 170,000 per month, and a prospect search module.
Unlimited does not mean free or uncapped. Both cap monthly sends, and the mailboxes themselves cost money: Smartlead sells mailbox setup as an option, for example $13 per domain per year plus $4.50 per mailbox per month for fresh Google or Outlook mailboxes.
What sets them apart: the structure of the offer
Smartlead sells a subscription on sending and contact storage, then options: client workspaces at $29 per client per month (white label included), SmartServers dedicated servers at $39 per server per month, and the SmartDelivery deliverability add-on in three tiers from $49 to $599 per month.
Instantly sells three families: bundled plans (sending, uploaded contacts, credits), a sending-only range, and a credits range for its database. Its Agency plan adds a dedicated IP system called SISR; the AI Reply Agent comes from the Scale plan up.
Plans displayed on September 29, 2026
| Plan | Price per month | Sends per month | Contacts and credits | Worth noting |
|---|---|---|---|---|
| Smartlead Base | $39 | 6,000 | 2,000 stored contacts, 2,000 verified emails | Client workspaces not offered |
| Smartlead Pro | $94 | 90,000 | 30,000 contacts, 30,000 verified emails | Client workspaces as an add-on |
| Smartlead Smart | $174 | 150,000 | Unlimited contacts, 50,000 verified emails | Flagged as the most popular plan |
| Smartlead Prime | $379 | 500,000 | Unlimited contacts, 170,000 verified emails | 3 client workspaces and 3 SmartServers included |
| Instantly Starter | $94 | 5,000 | 1,000 uploaded contacts, 1,500 credits | Database access and AI Sales Agent |
| Instantly Scale | $194 | 100,000 | 25,000 uploaded contacts, 5,000 credits | AI Reply Agent, advanced deliverability |
| Instantly Agency | $555 | 500,000 | 100,000 uploaded contacts, 10,000 credits | SISR dedicated IP system |
Two annual discounts are displayed: 17% at Smartlead, about 10% at Instantly on its bundled plans.
A calculation of our own, to be handled with care: the displayed price per thousand sends, obtained by dividing the monthly price by the monthly volume, is $1.04 for Smartlead Pro ($94 for 90,000), $1.16 for Smart and $0.76 for Prime, against $1.94 for Instantly Scale ($194 for 100,000) and $1.11 for Agency. These figures do not compare like with like: the Instantly plan includes data credits and AI agents that the Smartlead plan does not include in the same way. If you do not need the database, Instantly also offers a sending-only plan at $47 per month (5,000 emails and 1,000 uploaded contacts), to compare with Smartlead Base at $39 for 6,000 sends.
When to choose one or the other
Smartlead looks better suited if:
- you manage several clients or brands: optional client workspaces, white label and the three workspaces included in Prime seem designed for that;
- you already have your data and mainly need sending capacity, for which the displayed price per thousand sends is the lowest in our calculation;
- you want dedicated servers and optional deliverability modules.
Instantly looks better suited if:
- you are a single-brand team that wants to find prospects, enrich them and send from the same place;
- you want AI agents to write or reply, included in the bundled plans;
- your volume stays moderate and you prefer a single subscription to a stack of tools.
We do not test the deliverability of these tools: the official pages advertise customer figures, but those are testimonials, not independent measurements. Deliverability depends mostly on how your domains are configured and on the quality of your lists. For the basics of domain authentication, see our guide Outbound B2B deliverability: mastering SPF, DKIM and DMARC.
And Ember in all this?
Ember is not a bulk email sending tool. Lead Intelligence is a prospecting mission tool: discover, qualify and reach targeted prospects. If your difficulty is deciding whom to contact rather than sending a lot, our comparisons with each of the two tools show where each one sits: Smartlead vs Ember Lead Intelligence and Instantly vs Ember Lead Intelligence. To discover the tool, visit Lead Intelligence.
Further reading
The two closest published articles each compare one of these tools with Lead Intelligence. This one compares Smartlead and Instantly with each other, using the plans actually displayed.
Sources
- Smartlead: unlimited-mailbox outbound infrastructure with verified-lead credits: source S1
- Smartlead: unlimited-mailbox outbound infrastructure with verified-lead credits: source S2
- Instantly: AI outbound copilot with a credit-metered lead database: source S1
- Instantly: AI outbound copilot with a credit-metered lead database: source S2
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