Peeker
Alternative & Review

Peeker.ai was founded in January 2024 by Conrad Niedzielski and Connor Dixon. It is a cold email infrastructure provider focused on self-healing mailboxes. Its official site says the platform creates mailboxes, monitors performance, detects burned infrastructure, and swaps mailboxes before problems damage campaigns. It states that Peeker is trusted by 500+ leading cold email teams and monitors 200,000+ mailboxes in real time.

The product is best suited for teams that already understand cold email risk and want automatic replacement to be part of the infrastructure layer. Peeker lists Google and Microsoft Azure mailboxes, deliverability analytics, burn detection, automatic inbox swaps, automatic reconnects, bulk deployment, US ISPs, in-app support, and direct API integrations.

Peeker's main difference is operational recovery. Instead of only selling mailboxes, it emphasizes monitoring and replacement when mailboxes or domains become risky. The official FAQ says that if mailboxes get flagged for spam, Peeker offers premium domain swaps to replace current mailboxes without buying another subscription or stopping sending volume.

G2: No reviews found.
Trustpilot: No reviews found.

We also couldn't find any posts on Reddit mentioning Peeker.

🟢 Self-healing positioning is clear. Peeker explicitly focuses on burn detection, automatic swaps, and replacement workflows, which directly address one of the biggest scaling risks in cold email.
🟢 Simple per-mailbox pricing. The official pricing tiers are easy to understand: $3.50, $3.00, and $2.80 per mailbox, depending on volume.
🟢 Strong integration focus. Peeker states that it integrates with Instantly, Smartlead, EmailBison, Plusvibe, and other sending tools through API-based connections.
🟢 Useful public operating guidance. The FAQ gives practical sending guidance, including recommended inboxes per domain and common emails-per-mailbox assumptions.

🔴 SMTP is not clearly offered. Peeker's public page focuses on Google and Microsoft Azure mailboxes. Teams that need SMTP mailboxes may need a different provider.
🔴 Public review footprint is limited. The checked Trustpilot URL returned no accessible profile, and the G2 page did not provide a verified public score during research.
🔴 Cancellation is less flexible. Peeker's FAQ states that cancellation requires a 30-day period and does not allow early prorated cancellations.

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.
🟢 Self-Healing Rotation: An automated resting period for mailboxes every two weeks that clears provider flags and recovers reputation on autopilot.
🟢 API & MCP Automation: Create domains and mailboxes, export to your sequencer in one call – or manage it all from your AI assistant through our MCP server.

🔴 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 were interested in studying a product that, like us, offers self-healing mailboxes. We have carefully reviewed their website, and it appears our underlying principles differ slightly.

Peeker only deactivates 'burned' mailboxes and replaces them with active ones. Maildoso, however, splits your mailboxes into two groups: while one half is active, the other is 'resting.'

While Peeker focuses on recovering mailboxes that have already burned out, we focus on preventing them from burning out in the first place. During their 'rest' period, our mailboxes send only warmup emails, which continuously strengthens their reputation.

Want to see how it works? We are offering 300 mailboxes for a 30-day trial.