In 2026, getting your emails into the inbox is harder than ever.
According to Warmy’s State of Deliverability Report 2025, the average inbox placement rate across major ESPs sits at just 83.5% with spam placement rate at 6.7% and 9.8% emails missing and unaccounted for.
For high-volume outreach teams, the gap may be even more pronounced. This is the environment in which both Warmy.io and Instantly.ai operate. Understanding the difference between them is essential before committing your sending infrastructure to either.
The short answer: these tools serve fundamentally different purposes:
- Instantly.ai is a cold email outreach automation platform. It helps you find leads, build sequences, personalize at scale, and scale your pipelines.
- Warmy.io is an all-in-one email deliverability infrastructure tool. It ensures that when Instantly (or any sending tool) fires, those emails actually land in the inbox rather than the spam folder.
That said, both include email warmup capabilities. So if you’re evaluating your deliverability stack (whether as a solo SDR, an email marketer, an outreach agency, or an IT admin responsible for domain health) this guide gives you the technical clarity you need.
We’ve examined every warmup and deliverability feature side by side, so you can make an informed decision based on your actual sending volume and goals.
At a glance: Warmy vs. Instantly.ai side-by-side feature comparison
The table below covers every warmup and deliverability-related feature across both platforms.
Warmy.io
Instantly
Note: Several Instantly.ai deliverability features (inbox placement testing, email validation) require paid add-ons at additional cost, whereas Warmy includes these in its standard plans.
What is Instantly.ai and what are its core deliverability features?
Instantly.ai is a cold email outreach automation platform designed to help B2B sales teams and SDRs send personalized email sequences at high volume.
Its strength lies in the outreach layer of your sales motion, not in the deliverability infrastructure that makes outreach sustainable long-term.
Warmup and deliverability capabilities
- Instantly includes a built-in warmup feature, but it’s intentionally lightweight.
- The platform recommends a maximum of around 10 warmup emails per day, which is a conservative figure reflecting its role as a supplementary feature within a sales platform, rather than a specialised deliverability solution. As Instantly is capable of sending up to 500 000+ emails monthly, a warmup capability of only 10 emails a day seems lacking.
- Warmup by Instantly supports Google, Outlook, and custom SMTP connections.
- Warmup customization is limited to basic parameters like open rate, reply rate, and spam recovery.
- There is no multi-language support, no topic-based warmup, no click simulation, and no dedicated AI managing the warmup schedule.
For senders who are just starting out with a fresh domain and modest outreach volumes, this may be sufficient. For anyone running campaigns at scale or managing multiple client domains, it presents a significant gap.
Where Instantly falls short on deliverability
- Instantly does not offer a dedicated AI system for deliverability optimization.
- Its Inbox Placement and Email Validation features are both paid add-ons rather than included features.
- There is no Google Postmaster integration, no SPF or DMARC generators, no blacklist monitoring included natively, and no seed list testing across Gmail, Outlook, and Yahoo.
- The platform is not designed to diagnose or actively remediate inbox placement problems or damaged sender reputation scores.
Run a free deliverability test to see your domain health score.
Warmy's core features in comparison to Instantly
Warmy.io is purpose-built for one thing: making sure every email you send lands in the inbox. The difference in depth and scope is substantial.
Adeline AI: Warmy's proprietary deliverability engine
At the core of Warmy’s platform is Adeline, a proprietary AI that makes 20 million decisions daily all for the purpose of optimizing email deliverability for each user.
Rather than applying a generic ramp-up schedule, Adeline analyzes your current sender reputation, sending volume, engagement patterns, and intended goals to create a plan that fits your specific inbox. Then it adapts that plan in real time based on how mailbox providers respond.
Instantly has no equivalent. Its warmup operates on a fixed, low-volume model with no AI-driven adaptation.
Scale: 10,000+ warmup emails per day
Warmy supports more than 10,000 warmup emails per day across its network of over 1 million active mailboxes.
This is not just a volume game. It also reflects the scale of real, positive engagement signals being generated on behalf of your domain. For high-volume senders where deliverability penalties can cost real pipeline, this depth of warmup activity is what separates Warmy’s robust features from basic warmup features.
Supported providers
Warmy warms up mailboxes across 18+ email service providers, including Gmail and Google Workspace, Microsoft 365, Outlook, SendGrid, Yahoo, Mailgun, Brevo, Zoho, AOL Mail, Amazon SES, GoHighLevel, Elastic Email, SendPulse, Mailjet, SMTP.com, ExpertSender, and custom SMTP configurations. Meanwhile, Instantly supports Google, Outlook, and SMTP.
For agencies or enterprise teams operating across multiple sending environments, Warmy’s provider coverage eliminates the need for multiple tools.
Advanced warmup customization
Warmy’s warmup goes well beyond open and reply rate settings. Users can configure warmup emails according to:
- Language (30+ languages to choose from): critical if your outreach is not in English
- Topic: align warmup content to your actual niche for more relevant engagement signals
- Temperature and engagement patterns: control the aggressiveness of warmup behaviour
- Distribution per provider: allocate warmup volume across specific mailbox providers
- Spintax on user templates: warm up using variations of your actual email templates
- Warmup With Clicks: warmup emails can include click-through actions, which no Instantly warmup feature provides
This level of customization allows Warmy to produce warmup activity that closely mirrors real-world human behaviour, precisely what modern spam filters are trained to reward.
One G2 reviewer mentioned, “From everything I’ve tested, they offer the best warm-up system and the widest range of options to actively improve deliverability. For example, if you see that a client has an 80% Microsoft inbox distribution, you can simply adjust your mailboxes so that 70–80% of the warm-up traffic also goes to Microsoft. That way you’re not stuck warming up on a generic 50/50 split while actually sending most of your volume into Microsoft, which is exactly how accounts get burned.”
Seed lists, deliverability testing, and DNS tools
- Warmy includes seed lists across Gmail, Outlook, and Yahoo, enabling you to warm up specific providers according to your needs.
- Our Email Deliverability Test goes beyond basic inbox placement to include blacklist monitoring and DNS checks (SPF, DKIM, DMARC validation), all within the platform. While there is a free version for non-users, Warmy users can set up automatic weekly tests.
- Two additional free tools: an SPF Record Generator and DMARC Record Generator are available directly within Warmy and as standalone resources for any sender who needs to fix their SPF records without technical assistance. These tools matter because authentication failures remain one of the leading causes of inbox placement drops following recent bulk sender requirement updates.
The verdict: Choosing the right tool for your strategy
Warmy’s approach is built on behavioural intelligence: that inbox placement is earned through a positive domain reputation which is then impacted by overall infrastructure health and patterns of human-like activity that mailbox providers have learned to trust.
Instantly’s approach is built on a low-friction warmup feature that keeps your account active without requiring configuration.
Neither is wrong for its intended audience. But for senders who are serious about protecting a domain’s long-term reputation, the two approaches are not comparable.
Warmy.io and Instantly.ai are not competing products. They are complementary layers of a complete cold outreach stack. The fact that many Instantly users already run Warmy alongside it is a telling signal: Instantly handles what to send and who to send it to; Warmy ensures it gets there.
Choose Warmy if:
- You need advanced, AI-driven warmup beyond basic automation
- You manage multiple domains, clients, or mailboxes at scale
- You require infrastructure tools: SPF/DMARC generators, blacklist monitoring, DNS health checks
- You want dedicated expert support for deliverability issues
- You operate across providers beyond Google and Outlook
- You want the deepest possible visibility into why your emails succeed or fail
Ready to go deeper? Start your 7-day free trial of Warmy.io.
Which tool is better for agencies — Warmy or Instantly?
Warmy is the stronger choice for agencies. Its dedicated Agency Dashboard, white-label program, and capacity for warmup emails per month give agencies centralized control over multiple client domains. Instantly is built around outreach campaigns and lacks native agency-level deliverability management. For teams responsible for protecting multiple sender reputations simultaneously, Warmy provides the necessary scale and visibility.
What free tools does Warmy offer?
Warmy offers a comprehensive suite of free tools designed to support email infrastructure health, including an Email Template Checker (also available as a Chrome extension), an SPF Record Generator, a DMARC Record Generator, and a free Email Deliverability Test. These tools address the foundational setup most senders overlook, allowing users to diagnose and fix deliverability issues without committing to a paid plan.
Can I use Warmy and Instantly.ai together?
Yes! In fact, many Instantly users already rely on Warmy for deliverability. Instantly handles the outreach layer (sequences, lead finding, CRM), while Warmy manages the inbox health layer (warmup, blacklist monitoring, domain authentication). Using both in tandem means your Instantly campaigns benefit from Warmy-optimized sender reputation, resulting in higher inbox placement and stronger overall campaign performance.
