FrostMailer
Alternative & Review

According to LinkedIn data, the company was founded in January 2024 by Eanna Fitzgerald, Jason Park, and James Shields.

FrostMailer is a cold email mailbox provider for agencies and outbound teams. Its official site lists three mailbox categories: Google Workspace, Standard SMTP Inbox, and Microsoft Azure Tenant.

FrostMailer says it preconfigures SPF, DKIM, and DMARC, manages DNS, redirects, forwarding, and inbox health monitoring, and allows teams to connect mailboxes to major cold email platforms. Its workflow is simple: sign up, complete an onboarding form, and get mailboxes configured quickly, with 48 hours stated for Google and 30 minutes for SMTP.

FrostMailer publishes a few public scale claims. The homepage states Trusted by 100+ businesses; it also claims that partners and agencies generated hundreds of meetings and over €3,000,000+ in revenue from cold outbound, but this should be treated as an official marketing claim rather than an independently verified metric.

Trustpilot: 4.5/5, 22 reviews

"I’ve tried frostmailer and Winnr for inboxes, both shit lol. Right now trying inboxkit (GWS accounts), so far having similar issues." – Cold email deliverability

🟢 Multiple mailbox types. FrostMailer offers Google Workspace, SMTP, and Microsoft Azure mailboxes, which gives buyers more choice than single-ecosystem providers.
🟢 Low Azure price. The Azure Tenant plan is listed at €0.80 per mailbox, with 100 mailboxes, domain included, SPF/DKIM/DMARC, a two-week warmup, and 24-hour readiness (but because you can only send 2 emails per day, the benefit of the low price is completely negated).
🟢 Hands-off setup. FrostMailer emphasizes done-for-you DNS and mailbox configuration, which can reduce operational burden for agencies that do not want to manually configure authentication at scale.
🟢 SMTP minimum is low. The Standard SMTP Inbox plan lists a minimum order of 3 inboxes, making it easier to run a small test before committing to a larger setup. It is worth clarifying that three mailboxes are not enough to achieve any significant results in outbound. With only three mailboxes, you'll be limited to sending about 250 emails per week, which will likely result in only 1–2 positive replies.

🔴 Refund and trial terms are not clearly disclosed. The checked official homepage did not expose a clear money-back guarantee, refund policy, or free trial terms comparable to Maildoso's public 30-day guarantee.
🔴 Company transparency is limited. Public pages reviewed did not disclose founders, headquarters, legal entity, or detailed company history, which can matter for agencies choosing a long-term infrastructure partner.
🔴 Azure daily sending is very low. The Azure Tenant plan states up to 2 emails per inbox per day, which means teams may need a large number of mailboxes for meaningful campaign volume.
🔴 Reddit signal is negative. The direct Reddit experience found during research was unfavorable, and no broader set of verified Reddit success stories was found in the checked sources.

Maildoso is a cold outreach infrastructure provider – we offer domains, SMTP mailboxes, and Google Workspace accounts. The company was founded in August 2023 in Granite Bay, California, by Nikita Bykadarov (Nikita Maildoso).

While other providers offer shared or dedicated IPs, we have developed IP rotation. This means your emails are sent from hundreds of different IPs (making it harder for spam filters to detect a sending pattern), and whenever any IP gets blacklisted, we automatically swap it out for a clean one.

We have also implemented self-healing mailbox technology, which both restores burned-out mailboxes and protects your active email accounts.

The result?
As of May 2026, the spam rate across our entire network of mailboxes is around 5%.

G2: 4.7/5 (181 reviews)

"Tried it mainly because of the good price, but ended up sticking with it since deliverability’s been pretty stable so far" – Thinking about trying "Maildoso". Has anyone here used it? Is it actually better than other tools?

"I tested a small batch first and results were comparable to our Google setup. Ended up moving more campaigns there because of the lower cost. That's a good strategy, buy small package and compare with your current setup" – I want to try Maildoso. What do you guys think about it?

🟢 Dynamic IP Rotation: We rotate your IP addresses in real-time – if an IP gets flagged or blacklisted, we instantly swap it for a clean one before your campaign takes a hit, ensuring your emails consistently land in the primary inbox rather than getting stuck in spam.
🟢 Self-Healing Rotation: An automated resting period for mailboxes every two weeks that clears provider flags and recovers reputation on autopilot.
🟢 Global Customer Domain Tracking: Proprietary technology that allows you to safely include links without compromising your sender reputation.
🟢 Automated Inbox Placement Tests: Free email deliverability infrastructure testing every three days for all mailboxes, giving you real-time visibility into your health.

🔴 Conservative Limits: We suggest sticking to 15 emails a day per box to keep your domains healthy for the long run.
🔴 Google/SMTP Focus: We do not support Microsoft 365/Outlook/Azure environments at this time.
🔴 Lack of built-in warmup. We do not have an integrated warm-up yet, but we are currently working on it.

It’s tempting to choose a provider based solely on the lowest price, but budget infrastructure often leads to hidden costs. When deliverability drops, the consequences usually show up in three areas:

• Burned Leads: High-quality B2B data is expensive. If emails land in spam, those contacts never see the pitch, and the budget spent on data is lost.
• Damaged Domains: Fixing a domain flagged by spam filters can be a massive headache. Often, it’s easier to just buy a new one and start the warm-up process all over again.
• Missed Revenue: Every missed inbox is a missed meeting. In B2B sales, losing even one connection can mean missing out on thousands in closed revenue.

Cold email infrastructure is better viewed as an investment. Maildoso provides the technical tools to protect domain reputation and help keep emails in the primary inbox.

We strongly advise against using Azure tenants. Not only because they limit you to just 2 emails per day—which is 15 times less than the SMTP limit, making the effective cost per mailbox significantly higher—but also because of the reliability risk. We consistently hear reports of yet another Azure provider getting blocked, causing all customer mailboxes to be burned with no possibility of recovery.

As for Google Workspace (GW) and SMTP, they are worth a try. However, compared to Maildoso (where we also offer both GW and SMTP), our mailboxes are far more resilient thanks to IP rotation and our self-healing mailbox technology.