Comparison, Tools, Warmup
Instantly vs Smartlead vs Warmerly: Which Email Warmup Tool Is Right in 2026
All three warm your mailboxes and send your campaigns. They differ on what they meter, how they handle LinkedIn, and how deep the deliverability tooling goes. Here is the honest comparison, including where we (Warmerly) lose.
Updated 10 min read
In this article
All three offer warmup and send cold email campaigns. The differences: Instantly ($47/month) is the best-known brand and caps its entry plan at 5,000 emails a month; Smartlead ($39/month) caps entry at 6,000 emails; Warmerly ($19/month for 5 mailboxes) has no cap on campaign sends and native LinkedIn at $19 per account, but is younger with fewer integrations. Pick Smartlead or Instantly if you want unlimited connected mailboxes on one plan, Warmerly for flat pricing, LinkedIn and WhatsApp in the same sequence and daily authentication checks. Smartlead and Instantly both list API access in their feature tables, but their pricing pages do not show which plan includes it.
We make Warmerly, so read this with that in mind. Competitor prices were re-read from Instantly's and Smartlead's pricing pages on 15 October 2026, and the section on where Warmerly loses is meant seriously. Where a page was unclear or contradicted itself, we say so instead of quoting a figure.
The summary table
| Instantly | Smartlead | Warmerly | |
|---|---|---|---|
| Entry price | $47/mo ($37.60 annual), Growth | $39/mo ($32 annual), Base | Free plan, then $19/mo (Starter) |
| Mailboxes on entry plan | Unlimited | Unlimited | 5 (Starter), 25 (Growth, $49), 100 (Agency, $179) |
| Warmup | Unlimited, included on Growth | AI warmups listed; whether Base includes it is not clear on the page | Included on every mailbox |
| Entry plan volume | 1,000 contacts, 5,000 emails/mo | 2,000 contacts, 6,000 emails/mo | 5,000 active prospects, unlimited campaign sends |
| Next tier | Higher outreach tiers: the page shows conflicting prices and limits, so we do not quote them | Pro $94: 90,000 emails, 30,000 contacts | Growth $49: 25 mailboxes |
| Not listed on the pricing page | Not listed on the pricing page | Native, $19/mo per account | |
| WhatsApp steps | Not listed on the pricing page | Not listed on the pricing page | Yes, in the same sequence |
| API | Listed in its feature table; plan not shown | Listed in its feature table; plan not shown | Agency plan only |
| Deliverability monitoring | Warmup health score | Warmup-focused | Placement spot checks and daily SPF, DKIM and DMARC checks |
| Maturity and integrations | Established brand | Established brand | Youngest, fewest integrations |
Price: what each one meters
The three tools meter different things, and that decides which is cheapest for you. Instantly and Smartlead let you connect unlimited mailboxes but cap monthly emails and contacts: 5,000 emails and 1,000 uploaded contacts on Instantly Growth, 6,000 emails and 2,000 contacts on Smartlead Base. Warmerly does the opposite: it caps mailboxes per plan (5, 25 or 100) and does not cap campaign sends.
Cost by scenario
| Scenario | Instantly | Smartlead | Warmerly |
|---|---|---|---|
| Founder testing cold email, 1 mailbox, a few hundred sends | $47 | $39 | $0 (free plan: 1 mailbox, 100 campaign sends/mo) |
| 5 mailboxes, about 4,000 emails/mo | $47 | $39 | $19 |
| 20 mailboxes, about 20,000 emails/mo | A higher tier than Growth; price not confirmed | $94 (Pro: 90,000 emails, 30,000 contacts) | $49 (Growth) |
| Add one LinkedIn account | Not listed on its pricing page | Not listed on its pricing page | Plus $19 |
| 80 mailboxes for an agency | Unlimited accounts; the tier depends on volume | Unlimited accounts; the tier depends on volume | $179 (Agency, 100 mailboxes) |
At small scale Warmerly is the cheapest by a wide margin. At very high volume from a modest number of inboxes, the comparison narrows, because Instantly and Smartlead do not charge per mailbox. If you run 300 inboxes, a mailbox-capped plan is the wrong shape, and Instantly or Smartlead will fit better.
Warmup
All three run peer-to-peer warmup: your mailbox exchanges conversational mail with other mailboxes in a network, which open, reply, mark important and rescue messages from spam. Instantly's and Smartlead's help centers describe warmup pools made of their own users' mailboxes. Warmerly's network is smaller because we are newer, and warmup messages that land in spam are moved to the inbox, marked not spam and answered.
In practice, all three will warm a healthy mailbox with correct authentication. Warmup quality differences matter less than whether your SPF, DKIM and DMARC pass and whether you ramp new inboxes slowly.
Campaign sending
All three ship a campaign engine with multi-step sequences, A/B variants, stop-on-reply and a unified inbox for replies. Instantly and Smartlead have been around longer and likely connect to more third-party tools; check the integrations you need. Warmerly's engine adds LinkedIn and WhatsApp steps on the same timeline as email, and pre-launch checks that block a campaign with a missing merge variable instead of sending a broken first line to your list.
LinkedIn and multichannel
Neither Instantly's nor Smartlead's pricing page lists LinkedIn automation, so if you need it, check how each handles it and whether it costs extra. Warmerly runs LinkedIn itself at $19/month per account, with a human-paced warmup ramp for new or quiet accounts. LinkedIn has no free trial and is charged immediately.
API and integrations
Both Smartlead and Instantly list API access in their feature tables, but their pricing pages do not show which plan includes it, so check before you build on either. Warmerly's API is on the Agency plan only, and its integration list is shorter. If a specific integration is essential, check it before you move.
Deliverability monitoring
This is where Warmerly puts most of its effort. A placement test sends one message to a few target mailboxes and looks in the inbox, promotions and spam folders, as a spot check rather than a guarantee. SPF, DKIM and DMARC are checked daily on every domain, with an alert and fix instructions when a record breaks. We did not find placement testing or daily DNS monitoring on Instantly's or Smartlead's pricing pages, so if you need them, check what each includes on your plan.
Why this matters: warmup builds reputation, but it does not tell you when something breaks. A teammate adds a second SPF record, a DNS move drops the DKIM key, or one domain lands on a blocklist, and every tool keeps reporting the campaign as sent. The earlier you hear about it, the fewer emails go to spam before you fix it. If you stay on Instantly or Smartlead, run a placement test and a DNS check at least weekly, and always after changing providers or DNS hosts.
Where Warmerly genuinely loses
- Younger product, fewer integrations. Instantly and Smartlead have been sending at scale for longer and connect to more tools.
- Smaller warmup network. It is newer than Instantly's or Smartlead's.
- API only on Agency. Instantly and Smartlead list API access in their feature tables; check which plans.
- Mailbox caps. At several hundred inboxes, unlimited-mailbox plans from Instantly or Smartlead fit better.
- LinkedIn has no trial. The email plans do; LinkedIn is charged from the start.
Where Warmerly wins
- Price at small and mid scale: $19 for 5 mailboxes, $49 for 25, with no cap on campaign sends.
- A real free plan: 1 mailbox and 100 campaign sends a month, no card.
- Native LinkedIn and WhatsApp steps in the same sequence, no second subscription.
- Deliverability checks: placement spot tests, daily authentication checks with fix instructions, and spam rescue for warmup mail.
Three questions that decide it
Most teams can choose in five minutes by answering three questions honestly.
- How many inboxes will you run in six months? Under 100, all three fit and Warmerly is cheapest. Several hundred, Instantly or Smartlead fit the shape better because they do not charge per mailbox.
- Is LinkedIn part of the plan? If every sequence needs a LinkedIn step, a native channel is simpler than a second subscription. If LinkedIn is occasional, a separate tool next to Instantly or Smartlead is fine.
- Will you build on the API? If you are wiring the tool into your own dashboards, client portals or data pipeline, start with Smartlead and check the endpoints you need before you commit.
A fourth question matters only if deliverability is already hurting: do you know where your mail is landing? If the answer is no, the tool with placement tests and daily DNS checks will save more than any price difference.
Switching between them
Sender reputation belongs to your domains and mailboxes at Gmail and Microsoft, so it moves with you. To switch, reconnect the same mailboxes to the new tool, turn warmup off in the old one so two networks are not warming the same inbox, export your leads with unsubscribes and bounces included, and rebuild sequences by hand. Run the first week at a lower daily volume and check placement before returning to full speed.
The honest recommendation
- Building custom tooling on an API: check the API plan details of Smartlead and Instantly first.
- Hundreds of inboxes on one plan: Instantly or Smartlead.
- Up to 100 mailboxes at a flat price, LinkedIn and WhatsApp in the same sequence, and daily authentication checks: Warmerly.
- Already happy with a campaign tool: keep it, and use Warmerly for warmup and monitoring on the same mailboxes.
Frequently asked questions
Is Smartlead better than Instantly?
On their pricing pages Smartlead is cheaper at entry ($39 against $47) and allows more emails on its entry plan (6,000 against 5,000). Both list unlimited email accounts. Instantly's page shows conflicting prices for its higher tiers, so check them. Instantly states unlimited warmup on Growth; Smartlead lists AI warmups but is not clear about Base.
What is the cheapest alternative to Instantly and Smartlead?
Warmerly: a free plan with 1 mailbox and 100 campaign sends a month, then $19/month for 5 mailboxes with no cap on campaign sends, or $49 for 25. It is younger than both, with fewer integrations.
Do Instantly and Smartlead include email warmup?
Instantly states unlimited warmup on Growth. Smartlead lists AI warmups, but its pricing page does not make clear whether Base includes them. Warmerly includes warmup on every mailbox on every plan, including the free one.
Can Instantly or Smartlead do LinkedIn outreach?
Neither pricing page lists LinkedIn automation, so check before you rely on either for it. Warmerly runs LinkedIn natively at $19 per account per month, with no free trial.
Which has the best API: Instantly, Smartlead or Warmerly?
Both Smartlead and Instantly list API access in their feature tables but do not show which plan includes it on the pricing page, so check before you build. Warmerly's API is on the Agency plan ($179/month for 100 mailboxes).
Can I use Warmerly alongside Instantly or Smartlead?
Yes. Keep Instantly or Smartlead as the sender and connect the same Gmail or Microsoft mailboxes to Warmerly for warmup, placement tests and daily SPF, DKIM and DMARC checks. Turn off warmup in the other tool first so two networks are not warming the same inbox.
