Instantly's built-in warmup is included in all plans (starting at $37/month) and uses a network of 200,000+ real accounts to warm your sending domains. Strengths: large network, included in subscription cost, automatic optimization, warm while sending campaigns. Weaknesses: can't isolate warmup performance from campaign metrics, less control than standalone tools, effectiveness depends on network health. For most cold emailers, Instantly's warmup eliminates the need for a separate tool.
Instantly Warmup Review 2026: How It Works and Is It Effective?
Instantly Warmup: What You Get (and What You Don't)
Instantly includes email warmup in every subscription plan. For the majority of cold emailers, this eliminates the need for a standalone warmup tool like Warmbox or Mailreach. The warmup runs automatically in the background — connect your email account, enable warmup, and Instantly handles the rest.
But "included" doesn't mean "perfect." Here's what the warmup actually does and where it falls short.
How Instantly Warmup Works
Instantly's warmup network includes 200,000+ real email accounts. When you enable warmup on a connected account:
- Gradual sending: Starts at 2-5 warmup emails per day, increasing over 2 weeks
- Real engagement: Network accounts open, read, and reply to your warmup emails
- Spam rescue: If warmup emails land in spam, network accounts move them to inbox
- Parallel operation: Warmup runs alongside active cold campaigns
The warmup emails use varied subjects and content generated to look like natural business correspondence. They're tagged internally so they don't appear in your Instantly campaign metrics.
Strengths
No extra cost. Warmup is included in all plans. Compare this to paying $19-25/mailbox/month for Warmbox or Mailreach across 10 domains. At 10 domains, you're saving $190-250/month.
Largest network. 200,000+ accounts is one of the largest warmup networks available. More accounts mean more diverse sender-recipient pairs, which looks more natural to mailbox providers.
Continuous warmup. Warmup doesn't stop when you launch campaigns. It runs alongside your cold outreach, maintaining positive engagement signals even on days when campaign responses are low.
Practitioner note: The biggest practical advantage of Instantly's warmup is that it's zero-friction. Teams don't forget to set it up, don't have to manage a separate tool, and don't have to coordinate warmup timing with campaign launches. It just works in the background.
Weaknesses
No inbox placement testing. Instantly shows warmup metrics (emails sent, opened, replied) but doesn't test where your emails land across providers like Mailreach does. You know warmup is happening but can't verify inbox placement independently.
Less control. Standalone tools like Warmbox offer warmup "recipes" — different strategies for new domains, damaged reputation, or maintenance. Instantly's warmup is more automated with fewer customization options.
Network detection risk. With 200,000+ accounts in one network, mailbox providers may eventually detect patterns. Google and Microsoft are investing in identifying artificial engagement. This risk applies to all warmup tools, but larger networks may be easier to fingerprint.
Practitioner note: Instantly's warmup is "good enough" for 90% of cold emailers. The 10% who need more are either recovering from serious reputation damage (use Mailreach for its testing capability) or running infrastructure at scale where fine-grained control matters.
Instantly Warmup vs. Standalone Tools
| Feature | Instantly Warmup | Warmbox ($19/mailbox) | Mailreach ($25/mailbox) |
|---|---|---|---|
| Cost | Included | $19/mailbox/mo | $25/mailbox/mo |
| Network size | 200K+ accounts | 35K+ accounts | 20K+ accounts |
| Inbox placement test | No | No | Yes |
| Custom recipes | Limited | Yes | Basic |
| Provider support | All | All | All |
| Campaign integration | Native | Separate tool | Separate tool |
Who Should Use Instantly Warmup
Good fit: Anyone already using Instantly for cold email — just enable it. Teams warming 5+ domains who want to avoid per-mailbox warmup costs. Cold emailers who want zero-friction warmup.
Bad fit: Teams needing inbox placement testing (add Mailreach for testing only). Senders not using Instantly who need standalone warmup (use Warmbox or Mailreach).
The Bottom Line
Instantly's warmup is the most cost-effective option for cold emailers already on the platform. It's not the most configurable or feature-rich warmup tool, but it's included in your subscription and works automatically. For most teams, that's enough.
If you need inbox placement testing on top of warmup, add Mailreach for its spam test feature — use it for testing, not warmup.
For a comprehensive deliverability setup beyond warmup, schedule a consultation.
Sources
- Instantly: Warmup Features
- Instantly: Pricing
- Instantly: Help Center - Email Warmup
- EmailTooltester: Email Warmup Tools Comparison 2025
v1.0 · April 2026
Frequently Asked Questions
Is Instantly warmup included in all plans?
Yes. Warmup is included in all Instantly plans — Growth ($37/month), Hypergrowth ($97/month), and Light Speed ($358/month). There's no additional cost for warmup. This is a key advantage over standalone warmup tools that charge per mailbox.
How does Instantly warmup work?
Instantly connects your email accounts to a network of 200,000+ real accounts. The network exchanges emails with your account, opens them, replies, and marks them as important. This builds sending history and positive engagement signals that improve your reputation.
How long does Instantly warmup take?
Instantly recommends 2 weeks of warmup before launching cold campaigns. The warmup starts at 2-5 emails per day and gradually increases. You can see warmup metrics in the dashboard to track progress.
Can I warm up while sending campaigns on Instantly?
Yes. Instantly runs warmup alongside your active campaigns. The warmup emails supplement your campaign sends, maintaining positive engagement signals even while you're sending cold outreach.
Is Instantly warmup as good as Warmbox or Mailreach?
For most users, yes. Instantly's network is larger than most standalone tools. Standalone tools like Mailreach offer inbox placement testing that Instantly doesn't include. But for pure warmup, Instantly's built-in option is sufficient and saves the cost of a separate subscription.
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