Mailerr
Alternative & Review

Mailerr Ltd is a private company registered in London on 3 November 2025. Its platform focuses on provisioning premium cold‑email infrastructure. Users can register new domains or connect existing ones, with Mailerr automatically setting up SPF, DKIM and DMARC records and creating new mailboxes within seconds. Workspaces let agencies organise multiple clients, and the dashboard allows management of multiple Google Workspace accounts under one admin.

Their deliverability is enhanced by dedicated US‑based IP addresses and custom tracking domains, which help monitor blacklist status, spam reports and bounces. Mailerr recommends sending 30–50 emails per mailbox per day and does not offer refund.

Trustpilot: No reviews found
G2: No reviews found

No relevant Reddit discussions about Mailerr’s performance or deliverability were found during research.

🟢 Automated infrastructure: one‑click domain registration and DNS setup (SPF, DKIM, DMARC) with new mailboxes ready within seconds.
🟢 Dedicated US IPs & tracking domains: isolated IP reputation and custom tracking domains help monitor blacklists, spam complaints and bounces.
🟢 Workspace management: supports multiple clients and allows management of several Google Workspace accounts under one admin.
🟢 Scalability & deliverability: third‑party reviews note that Mailerr provides enhanced deliverability and unlimited mailbox potential for agencies.

🔴 High cost & extra fees: per‑mailbox pricing of $3.33–$4.00 and annual domain fees make Mailerr expensive. There is no refund policy.
🔴 Limited analytics: while it monitors blacklists and spam reports, it lacks campaign‑level reporting and deliverability analytics.
🔴 Scaling constraints: additional mailboxes cost $3.5–$4 each and plan limits restrict the number of domains and mailboxes.

Maildoso isn’t a complex management suite or a sequence builder – we know that real outreach needs a rock-solid foundation. We understand how the inbox works way better than those "all-in-one" platforms. From our self-healing mailbox rotation to automated email deliverability infrastructure checks, we do all the technical "dirty work" for you, so you can stop worrying about the tech and get back to closing deals.

We provide high-authority mailboxes designed to stay healthy for months, not weeks, allowing your outreach team to focus on the 1% of deals that matter rather than the 99% of tech that usually breaks. It’s a specialized environment for agencies looking for a reliable SMTP mailbox for agencies that have graduated from generalist tools.

G2: 4.7/5 (181 reviews)

"For the price point it's been worth it for us. We're sending around 1,500-2,000 emails/day across those 100 mailboxes and reply rates have been decent (2.8-3.2% depending on the campaign, but that's more about copy and targeting obviously). The infrastructure has been stable enough that i'm not constantly putting out fires anymore which was the whole point." (My Maildoso review after testing 100 mailboxes over 3 months)

"Checking back in after another 14 days of volume. We’re officially at 500 mailboxes now and the infrastructure is holding up remarkably well. Only 14 boxes are currently in the "cooling off" period, which is less than 3% of the fleet (totally manageable). Reply rates are hovering at 2.3%, keeping our cost per reply at that $0.10 mark. Honestly, the biggest win so far isn't just the price, it’s the lack of "clustering" issues that usually plague us at this volume on GW. (The truth about SMTP in 2026: A very deep Maildoso review (300k emails sent))"

🟢 Dynamic IP Rotation: We don't just "aim" for the inbox – we engineer it. Our system automatically rotates 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 System: An automated resting period for mailboxes every two weeks that clears provider flags and recovers reputation on autopilot.
🟢 Hybrid Flexibility: The ability to seamlessly blend high-authority Google Workspace accounts with high-volume SMTP mailboxes.
🟢 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.
🟢 Unlimited Technical Audits: Free live sessions with experts who resolve up to 80% of issues through deep server-level forensic audits.
🟢 Advanced Captcha Protection: Technical barriers that shield your outreach domains from being linked back to your primary corporate assets.

🔴 Conservative Limits: We suggest sticking to 15 emails a day per box to keep your domains healthy for the long run. You are free to send more if you choose, but be aware that aggressive "blasting" is a fast track to burning your reputation.
🔴 Google/SMTP Focus: We do not support native Microsoft 365/Outlook environments at this time.

Based on their website, Mailerr only offers basic features that most other providers include by default.
We don’t see any direct mention of dedicated IPs on their site—but even if they offered them, we have a much more powerful feature: IP rotation.

• With Shared IPs: If just one user on the network gets blacklisted, you go down with them.
• With Dedicated IPs: If one of your own mailboxes gets blacklisted, you're stuck with no way out.
• With IP Rotation: Not only are you sending through thousands of different IPs (making it impossible for spam filters to catch a pattern), but any suspicious IP is automatically replaced with a clean one, ensuring your sending never stops.

And let’s be honest, Mailerr’s pricing is above market average. There are plenty of other options available at much lower rates.
However, we always welcome testing. If you have the time and budget, you could grab a small batch of mailboxes to see how they perform – though we’d recommend investing the rest of your budget into more reliable tools.