# Email Warmup Tools for Agencies (2026): Unlimited Mailboxes and Pricing Compared

URL: https://warmerly.com/email-warmup/for-agencies
Published: 2026-10-13

> Email warmup tools for agencies in 2026: Instantly, Smartlead, Warmy, TrulyInbox, MailReach and Warmerly on unlimited mailboxes, clients and pricing.

For an agency with lots of mailboxes, the email warmup tools with unlimited mailboxes are Instantly (from $47/month), Smartlead (from $39/month) and TrulyInbox (from $29/month), each capped on volume instead. MailReach charges $19.50 per mailbox. Warmerly's Agency plan is $179/month for 100 mailboxes shared across unlimited client workspaces, with sending included.

Most email warmup tools were priced for one founder with one domain. An agency runs ten, fifty or a hundred mailboxes across client domains, and two questions decide the tool: what does it cost at 25, 50 and 100 mailboxes, and can each client's mailboxes, campaigns and data sit apart from the others? This page answers both for the tools agencies ask about most in 2026. Every competitor figure below was read from the vendor's own pricing or help page in October 2026.

## What an agency needs from an email warmup tool

- A pricing model that survives growth. Per-mailbox pricing multiplies with every client you sign. Unlimited-mailbox pricing does not, but it usually caps something else: emails, contacts or daily warmup volume.
- Per-client separation. Each client's mailboxes, campaigns, leads and reports in their own space, so one client never sees another's data and you can hand off or close a client cleanly.
- Gmail and Outlook support at scale. Client mailboxes arrive on Google Workspace, Microsoft 365 and assorted hosts. How each tool connects them decides how long onboarding a client takes.
- Alerts before the client notices. Daily SPF, DKIM and DMARC checks and reputation alerts, so a broken DNS record does not quietly stop a client's pipeline.
- One bill. Whether clients are billed through your account or each needs its own subscription changes the real cost more than the headline price.

## Email warmup tools with unlimited mailboxes or flat pricing in 2026

**Email warmup tools for agencies: unlimited mailboxes, client workspaces and pricing (checked October 2026). Monthly billing in USD; annual billing is cheaper on most. Verify on the vendor's site before buying.**
| Tool | Entry price | Mailboxes | What is capped instead | Client separation |
| --- | --- | --- | --- | --- |
| Instantly | $47/mo (Growth) | Unlimited | 5,000 emails and 1,000 contacts a month on Growth | Workspaces, but each workspace needs its own paid subscription |
| Smartlead | $39/mo (Base) | Unlimited | 6,000 emails and 2,000 contacts a month on Base | Client workspaces as an add-on from Pro ($94/mo); 3 included on Prime ($379/mo) |
| TrulyInbox | $29/mo (Starter) | Unlimited | Daily warmup emails across all accounts: 200 Starter, 1,000 Growth, 3,000 Scale | One multi-account dashboard; no client workspaces described |
| MailReach | $19.50 per mailbox/mo | Per mailbox | Nothing; you pay for each mailbox | Agency pricing on request |
| Warmy | From $49/mo | Not published | Volume-based; no mailbox counts published | Agency account with client list and access levels |
| Warmerly | $19/mo (5 mailboxes) | 5, 25 or 100 by plan; Agency $179/mo for 100 | Mailbox count; sending is not metered | Unlimited client workspaces on Agency, one shared pool, one bill |

## Cost at 25, 50 and 100 mailboxes

Headline prices hide the shape of each model, so here is what each tool costs as an agency grows. Where a tool caps volume rather than mailboxes, the question is whether the cap still fits once every client is running.

- MailReach at its $19.50 list rate, before any volume discount: $487.50 a month for 25 mailboxes and $975 for 50. Past 100 it quotes. Its calculator shows discounts but does not publish the thresholds.
- TrulyInbox: unlimited accounts, but the daily warmup volume is shared. On Growth ($99/mo) 1,000 warmup emails a day spread over 50 mailboxes is 20 each; over 100 it is 10. Its Scale plan ($199/mo, 3,000 a day) is the one it labels for agencies.
- Instantly: $47 covers unlimited accounts in one workspace, but sending stops at 5,000 emails a month on Growth; Hypergrowth ($97/mo) lifts it. If you separate clients into workspaces, each workspace is its own subscription, so five clients means five plans.
- Smartlead: $39 covers unlimited mailboxes with 6,000 emails a month. Client workspaces need Pro or above as an add-on whose price its help center does not list, so ask before budgeting; Prime ($379/mo) includes 3.
- Warmerly: 25 mailboxes fit Growth at $49/month in one workspace. Client workspaces are an Agency feature, so an agency that wants each client separate is on Agency at $179/month, which covers up to 100 mailboxes in total across every client.

> **The honest catch with Warmerly at 25 to 50 mailboxes**: If you have 30 mailboxes and want each client in its own workspace, you pay $179 for capacity you are not yet using. A tool like TrulyInbox or Smartlead Base is cheaper at that size if you can live without per-client separation. Warmerly's Agency plan earns its price nearer 100 mailboxes, or when you also send the campaigns from it.

## How Warmerly's Agency plan handles client workspaces

On the Agency plan you can create as many client workspaces as you need. Each one has its own mailboxes, campaigns, leads and inbox, and none of them carries its own subscription: they draw from the Agency plan's allowances as one pool, and everything is billed to the Agency workspace. A new client workspace skips the setup wizard and inherits your sender details, so it is ready to connect mailboxes straight away.

The limits are worth knowing before you commit:

- The 100 mailboxes are a total across the Agency workspace and every client workspace, not 100 per client.
- There is no published plan above 100 mailboxes. If you run more, talk to us before you buy.
- Warmerly does not offer white labelling. Clients you invite see Warmerly, not your brand.
- Hosted OneMail mailboxes are ordered on the Agency workspace, not inside a client workspace.
- If the Agency plan ends, each client workspace needs its own plan, and the Free plan is not available for an extra workspace.

What comes with it: warmup on every connected mailbox, campaign sending across email, LinkedIn and WhatsApp with no cap on sends (each mailbox keeps its own safe daily limit), daily SPF, DKIM, DMARC and MTA-STS checks, API access, and reputation alerts by email, webhook or Slack. LinkedIn accounts are billed separately: $19/month for one, less per account in packs.

## Which email warmup tool fits which agency

- You already run campaigns in Instantly and keep everything in one workspace: stay on Instantly; warmup is included and unlimited.
- You want a strong API and plan to build client tooling around it: Smartlead, on Pro or above for client workspaces.
- You only need warmup, on many mailboxes, lightly: TrulyInbox, as long as its shared daily volume still gives each mailbox enough.
- You want per-mailbox placement scores and run a handful of high-value mailboxes: MailReach.
- You want a managed relationship and do not mind a quote: Warmy.
- You want warmup and unmetered sending for up to 100 client mailboxes on one bill, with each client separate: Warmerly Agency.

**Keep reading**
- [How cold email agencies use Warmerly day to day](https://warmerly.com/use-cases/cold-email-agencies)
- [14 best email warmup tools, priced side by side](https://warmerly.com/email-warmup/best-tools)
- [Warmerly vs Smartlead: the full head-to-head](https://warmerly.com/compare/smartlead)
- [Warmerly vs TrulyInbox: flat-rate vs volume-capped unlimited](https://warmerly.com/compare/trulyinbox)
- [Warmerly pricing and plan limits](https://warmerly.com/pricing)

## Questions

### Which email warmup tools offer unlimited mailboxes?

As of October 2026, Instantly (from $47/month), Smartlead (from $39/month) and TrulyInbox (from $29/month) all allow unlimited mailboxes. Each caps something else instead: Instantly and Smartlead cap monthly emails and contacts, and TrulyInbox caps daily warmup emails shared across all accounts.

### What is the cheapest email warmup tool for an agency with 50 mailboxes?

It depends on what you need beyond warmup. For warmup alone, an unlimited-mailbox tool such as TrulyInbox costs less than paying $19.50 per mailbox at MailReach ($975 a month for 50). If you also want campaign sending and each client in its own workspace, Warmerly's Agency plan covers up to 100 mailboxes for one monthly price.

### Can I keep each client's mailboxes separate?

In Warmerly, yes: the Agency plan includes unlimited client workspaces billed through one account. Smartlead offers client workspaces from its Pro plan as an add-on and includes 3 on Prime. Instantly has workspaces, but its help center says each workspace needs its own paid subscription.

### Does Warmerly's Agency plan include white labelling?

No. Warmerly does not offer white labelling. Client workspaces keep each client's mailboxes, campaigns and data separate, but anyone you invite sees Warmerly's interface.

### What happens if my agency needs more than 100 mailboxes on Warmerly?

The Agency plan covers 100 mailboxes in total across all client workspaces, and there is no published plan above it. If you run more than 100, contact Warmerly before buying rather than assuming a larger tier exists.

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Source: https://warmerly.com/email-warmup/for-agencies
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