Best email warmup tools
A new mailbox has no sending history, and spam filters treat that as a red flag. Warmup builds the history before your real outreach starts.
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Instantly wins for a team that already sends through it, since warmup comes free on every plan. A standalone warmup tool earns its place for a mailbox that sends through a platform with no warmup of its own.
The short answer
- Instantly includes unlimited email warmup on every Outreach plan, starting at $47/mo, with no separate warmup fee.
- Standalone tools like Warmup Inbox charge per inbox per month: $15/inbox/mo on Basic up to $79/inbox/mo on Max. That adds up fast across a pool of a dozen or more mailboxes.
- Warmup trades real-looking mail with a network of other warmed inboxes. Volume goes up bit by bit, so the mailbox builds a normal sending pattern before real outreach begins.
- The main reason to pay for a standalone tool is sending through a platform, or a plain mail provider, that has no warmup built in.
How we compared these
We checked whether warmup comes free inside a sending platform or is sold on its own, and what a standalone tool costs per mailbox. We read each vendor's pricing page in September 2026.
We also checked how many warmup emails a day each tier sends. A slow ramp on a cheap plan can take much longer to get a mailbox to full volume than a fast ramp on a pricier tier. That changes the real cost of getting a new domain ready to send at scale.
Email warmup comparison
| Tool | Starting price | Bundled or standalone | Cost model | Best for | Not for |
|---|---|---|---|---|---|
| Instantly | $47/mo Growth plan | Built into the sending platform | Unlimited warmup on every plan, no per-mailbox fee | A team that already sends cold email through Instantly | A team on a different sending tool that only wants warmup |
| Warmup Inbox | $15/inbox/mo Basic (75 messages/day); $49/inbox/mo Pro (250/day); $79/inbox/mo Max (1,000/day) | Standalone, works with any mail provider | Monthly fee per mailbox, tiered by daily warmup volume | A mailbox that sends through a tool with no warmup built in | A team whose sending tool already has warmup, since you'd pay twice |
Figures checked on vendor pricing pages, September 2026, including warmupinbox.com/pricing.
The field, ranked
1. Instantly (bundled warmup)
Warmup is free on every Instantly plan, from $47/mo. Once you connect a mailbox, it trades real-looking mail with a large network of warmed accounts. If you already send through Instantly, it's the clear pick, with no extra line item to track. Best for: a team that sends and warms from the same tool, with no extra setup. Not for: a team on a different sending tool with no warmup built in.
2. Warmup Inbox
Warmup Inbox works with any mailbox, whatever tool you send from. It costs $15/inbox/mo (75 emails a day) up to $79/inbox/mo (1,000 a day), based on how fast you need to ramp. Best for: a mailbox on a plain mail provider or a tool with no warmup, above all one that must be ready for volume soon. Not for: a team that already pays for warmup elsewhere, since paying for both is a wasted line item.
How to choose
Choose Instantly if you send cold email through it, since warmup is free on every plan from $47/mo. Choose Warmup Inbox if your mailbox sends through a tool with no warmup, from $15/inbox/mo, and pick a higher tier when the mailbox must be ready for volume soon.
Warm the right mailboxes, too. Warmup belongs on new mailboxes on a second domain you bought for outreach. A founder's main inbox already has years of normal sending history and needs none. Running it through a warmup tool wastes money and mixes bot traffic into an inbox real people rely on every day. Inboxes used only for team mail, or for replies to leads who expect to hear from you, don't need warmup either.
Questions
- How long does warmup take before a mailbox is ready to send at volume?
- A common pattern runs several weeks. Daily volume goes up bit by bit before a new mailbox sends at full cold outreach levels. The exact time depends on how fast you ramp and the mailbox's starting reputation.
- Is bundled warmup as good as a standalone warmup tool?
- For most teams, yes. Each vendor does the same thing: it sends real-looking mail to a network of other warmed inboxes. The main reason to buy a standalone tool is a mailbox that sends from a platform with no warmup of its own.
- Can warmup fix a mailbox that is already flagged?
- It can help rebuild reputation over time, but it's not a fast fix. A badly burned domain is often better replaced than nursed back. Warmup works best before real sending starts, not as a rescue after the damage. If a domain is on a major blacklist, expect weeks of clean sending before its reputation comes back, if it comes back at all.
- Does SalesCrew include warmup?
- Disclosure: SalesCrew is our product. It runs your sender pool and the daily cap on each mailbox. It also syncs your Instantly senders and domains, so the mailboxes you warm there show up in the pool.