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FrostMailer

Cold email infrastructure, ready in 24 hours

Deliverability
For AI agents
APILimited readiness
About

What is FrostMailer

FrostMailer automates the provisioning and configuration of cold email mailboxes across Azure, Google Workspace, and SMTP, with DNS authentication records (SPF, DKIM, DMARC) preconfigured on every inbox. It's built for agencies managing outbound at scale and SDRs or BDRs who need inboxes spun up fast without touching DNS settings manually. The standout capability is the Microsoft Azure tenant option — 100 mailboxes plus a .com domain for €0.30 per mailbox — which makes it one of the lower-cost entry points for bulk cold email infrastructure available today. Inboxes also go through a warm-up process and ongoing health monitoring, and new accounts can be exported via CSV for direct import into tools like Instantly or Smartlead. The main limitation is volume throughput: the platform caps sends at two emails per inbox per day, so teams running high-frequency sequences will need a large number of inboxes to compensate.

Deliverability
Capabilities

Key features

Deliverability infrastructure

warmup, spam tests, and sender reputation

Our verdict

Vanderbuild take

FrostMailer is a cold email infrastructure provisioning tool — it sits at the deliverability layer and does one thing: get inboxes configured and ready to send for agencies and SDR/BDR teams without the manual DNS overhead. The API exists, but agentic readiness is limited — you can call it programmatically, but don't expect to build a fully autonomous inbox-spinning workflow on top of it without hitting friction in the integration layer. At budget tier 1, the pricing is near-free to test, especially on the Azure side, which makes it low-risk to evaluate against your current infrastructure setup. The hard ceiling to know going in: two emails per inbox per day means you're managing inbox count as a scaling lever, not send frequency — teams running aggressive sequences will need to provision a lot of mailboxes to hit meaningful daily volume.

Mateusz Sekta
Founder, vanderbuild
Learn more

Our Resources

The wedge

Agentic stack profile

API
Available

Programmatic access available.

Programmatic access available.

Agentic readiness
Limited

Usable but with caveats — rate limits, brittle endpoints.

API exists but is rate-limited, brittle, undocumented, or hidden behind enterprise plans. Use with caution in production agent workflows.

Stack role
Deliverability

Where this tool slots into an agentic pipeline.

Plays the role of Deliverability in an agentic pipeline. Use it to keep email sending reputation healthy — warmup, spam tests.

Compare

FrostMailer alternatives

Tools that solve a similar problem — compared at a glance.

FrostMailer(this tool)
Pricing
Usage-based
Budget
$
Best for
Agency, SDR / BDR
Readiness
Limited
API
Yes
Infraforge
Pricing
Usage-based
Budget
$
Best for
SDR / BDR, Agency
Readiness
Limited
API
REST
Mailpool
Pricing
Seat-based
Budget
$
Best for
SDR / BDR, Founder
Readiness
Limited
API
REST
Answers

Frequently asked questions

Does FrostMailer have a public API?

Yes — FrostMailer ships a public API. Note the API is rate-limited or enterprise-gated, so plan integrations accordingly.

How much does FrostMailer cost?

FrostMailer: pricing is usage-based, expect entry tier ($) spend. Full pricing page: https://www.frostmailer.com/.

Who is FrostMailer best for?

FrostMailer is built for Agency, SDR / BDR. Fits Solo, SMB (1-50)-sized teams.

How well does FrostMailer fit an agentic sales stack?

Tier: Limited. An API exists but it's rate-limited, brittle, or enterprise-gated. Plan integrations carefully.