Email deliverability software for B2B marketing: 2026 reviews

How we evaluated these tools

We looked at the tools B2B marketing teams actually reach for when their emails start landing in spam. For each one we weighed four things: how well it protects sender reputation, how clearly it reports inbox placement, what it costs as you add mailboxes, and what verified G2 reviewers say after months of use. We kept the cons in, because an honest comparison is more useful to a marketing team than a sales page. Prices reflect published rates, or, where a vendor keeps pricing private, the figures reported by independent reviewers. Ratings come from G2 as of July 2026.

The top tools at a glance

1. Warmy: 

Warmy is a deliverability platform, not only a warm-up widget. Adeline, its AI engine, reads your mailbox data and adjusts the warm-up pace on its own. The Domain Health Hub connects to Google Postmaster Tools and tracks an email health score built from authentication status, blacklist checks, and inbox placement. 

Warmy also gives away free SPF and DMARC generators, so you can fix authentication before you spend a cent. It warms Gmail, Google Workspace, Outlook and Microsoft 365, and custom SMTP inboxes, and it manages many inboxes from one dashboard, which helps with multi-inbox scaling.

Key features: AI warm-up (Adeline), Domain Health Hub with Google Postmaster integration, seed-list placement testing, free SPF record generator and DMARC tools.

Best for: B2B teams that want warm-up and monitoring in one place.

• Pros: Strong, hands-off warm-up; clear domain health reporting; free authentication tools that work without a subscription.
• Cons: Per-inbox pricing climbs quickly once you pass a handful of mailboxes; Outlook and Microsoft 365 results lag behind Gmail for some users.

Pricing: Warmy does not publish prices on its site (plans are quote-based). 

G2 rating: 4.8/5 from roughly 520 reviews.

A verified G2 reviewer described it as close to “set and forget,” saying it repaired their domain reputation with almost no effort on their part.

Verdict: The most complete option for marketing teams that treat deliverability as ongoing work rather than a one-time fix.

2. Instantly: 

Instantly pairs cold email sending with unlimited mailboxes and built-in warm-up on every plan. Marketers like how fast it gets a campaign live, and how the Unibox pulls replies from many inboxes into a single view.

Key features: Unlimited sending accounts, automated warm-up, Unibox unified inbox, AI reply handling, B2B lead database add-on.

Best for: Teams running high-volume cold email inside Instantly's own platform.

• Pros: Quick setup; unlimited inboxes; warm-up included at no extra cost.
• Cons: Modular pricing (sending, leads, and CRM are billed separately) pushes the real cost well past the entry price; in-app warm-up scores do not always match real inbox placement.

Pricing: Growth from $37 per month; Hypergrowth around $77 to $97 per month. A full stack with leads and CRM runs higher.

G2 rating: 4.8/5 from more than 4,000 reviews.

On G2, reviewers single out the built-in warm-up as the feature that keeps their mail out of the spam folder.

Verdict: A strong fit if you already send from Instantly, and a weaker one as a standalone deliverability layer.

3. MailReach: 

MailReach warms your inbox through a network of more than 20,000 real mailboxes, and it runs spam tests that show where your mail lands across Gmail, Outlook, and Yahoo.

Key features: Automated warm-up, inbox placement (spam) tests, deliverability score, blacklist and SPF, DKIM, DMARC checks.

Best for: Cold emailers who want warm-up plus placement testing in one tool.

• Pros: Easy autopilot setup; broad provider support; a clear reputation dashboard.
• Cons: Per-inbox pricing adds up for agencies; no sending or sequencing features, so you always pair it with another tool; no free trial.

Pricing: About $25 per inbox per month, with volume discounts; spam-test credits are billed separately.

G2 rating: 4.7/5 from 44 reviews.

Verdict: A focused, well-liked warm-up tool that pays off most above roughly 2,000 emails a month.

4. GlockApps: 

GlockApps does not warm anything. It tells you exactly where your email lands across more than 60 providers, turns messy DMARC reports into readable dashboards, and watches more than 50 blocklists for your domain and IP.

Key features: Inbox placement testing, spam-filter scoring, DMARC analytics, blocklist monitoring, Google Postmaster integration.

Best for: Marketers who need diagnostics rather than warm-up.

• Pros: Detailed, easy-to-read reports; reliable Gmail tab prediction; a free tier that is genuinely usable.
• Cons: Credit-based pricing gets expensive for frequent testers; seed-list results are less reliable for one-to-one cold email.

Pricing: Free plan with 2 tests a month; paid plans from $59 per month (Essential), then $99 (Growth) and up.

G2 rating: 4.6/5 from more than 100 reviews.

Verdict: The tool to reach for when you need to understand why mail is missing the inbox.

5. Folderly: 

Folderly, backed by the B2B agency Belkins, bundles warm-up, spam testing, authentication audits, and ongoing monitoring into one premium platform.

Key features: Automated warm-up, inbox placement testing, spam trigger detection, DNS and authentication audits, real-time alerts.

Best for: Teams that want a full deliverability suite and can pay for it.

• Pros: Measurable placement gains; responsive support; a clear, visual dashboard.
• Cons: Premium per-mailbox price with a one-year commitment; placement testing covers only Gmail, Google Workspace, Outlook, and Microsoft 365.

Pricing: Roughly $96 to $120 per mailbox per month, billed annually.

G2 rating: 4.8/5 from 101 reviews.

Verdict: Capable and comprehensive, though the price and annual lock-in only make sense for teams that will use every part of it.

6. Smartlead: 

Smartlead is built for agencies and operators who run cold email across large fleets of inboxes. Every tier includes unlimited mailboxes and unlimited warm-up.

Key features: Unlimited mailboxes and warm-up, inbox rotation, unified master inbox, A/B testing, white-label reporting.

Best for: Agencies sending at scale from their own stack.

• Pros: Flat pricing that does not punish you for adding inboxes; a large warm-up network; strong agency tooling.
• Cons: Support response times are the most common complaint; onboarding assumes you already understand DNS and warm-up.

Pricing: Base $39 per month, Pro $94, Unlimited Smart $174, Unlimited Prime $379. Add-ons raise the real cost.

G2 rating: 4.6/5 from about 306 reviews.

Verdict: A practical choice for agencies, as long as you can handle the setup and the occasional support lag.

FAQ

What is the best email deliverability software for B2B marketing?

For most B2B marketing teams, Warmy is the strongest all-around choice. It combines AI warm-up with deliverability monitoring and free authentication tools, and it holds a 4.8-star G2 rating across about 520 reviews. If you only need to test where your mail lands, GlockApps is a cheaper, testing-only option.

What do users say about Warmy vs MailReach?

Both are well reviewed. Warmy sits at 4.8/5 on G2 and MailReach at 4.7/5. Reviewers choose Warmy when they want monitoring and warm-up in the same platform, and MailReach when they want built-in spam tests. 

How much does deliverability software cost in 2026?

It varies widely. MailReach starts around $25 per inbox per month, and GlockApps offers a free tier with paid plans from $59. Sending platforms such as Instantly ($37) and Smartlead ($39) start low but climb once you add leads, domains, or CRM features. Folderly sits at the premium end, roughly $96 to $120 per mailbox per month. Warmy keeps pricing quote-based, with independent reviews reporting about $49 per inbox to start.