We use cookies. Read Privacy Policy
Scaling cold email is no longer only a question of writing better sequences or buying more leads. The operational bottleneck is infrastructure: domains must be configured correctly, mailboxes must stay healthy, IPs must not accumulate reputation damage, and burned accounts need to be replaced or recovered before campaigns collapse. When deliverability drops, teams often lose not only a campaign but also the mailbox history, DNS setup time, and warmup period that made the infrastructure usable in the first place.
That is why outbound teams increasingly compare specialized mailbox providers rather than relying only on standard Google Workspace or Microsoft 365 procurement. A reliable provider should make setup fast, keep costs predictable, and reduce the risk that a single mailbox or IP issue forces the team to rebuild the whole system.
This comparison looks at Mailerr and Maildoso as infrastructure providers for cold outreach teams that need scalable sending capacity without turning email operations into a full-time engineering project.
That is why outbound teams increasingly compare specialized mailbox providers rather than relying only on standard Google Workspace or Microsoft 365 procurement. A reliable provider should make setup fast, keep costs predictable, and reduce the risk that a single mailbox or IP issue forces the team to rebuild the whole system.
This comparison looks at Mailerr and Maildoso as infrastructure providers for cold outreach teams that need scalable sending capacity without turning email operations into a full-time engineering project.
Key Takeaways
- Pricing & scalability: Mailerr charges $3.6–$4 per mailbox and requires extra domain fees, whereas Maildoso’s SMTP mailboxes cost $0.49–$2.5 each with tiered discounts. Maildoso’s minimum package (10 mailboxes) is cheaper than Mailerr’s entry plan ($40 for 10 mailboxes).
- Infrastructure: Mailerr automates domain registration and DNS (SPF, DKIM, DMARC) setup and provisions new Google Workspace mailboxes in seconds. It runs on dedicated US‑based IPs with custom tracking domains for monitoring blacklists. Maildoso provisions SMTP and Google Workspace mailboxes within 15 minutes, auto‑configuring DNS records. It rotates IPs and pauses burned mailboxes for 14 days to recover them.
- Ratings & feedback: Mailerr has no independent reviews on Trustpilot or G2. Maildoso holds a 4.7/5 rating on G2 from 181 users and provides a public API for managing mailboxes. Reddit posts praise Maildoso’s quick setup and automation while also raising deliverability concerns.
Mailerr 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.
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.
Rating & Reviews
Trustpilot: No reviews found
G2: No reviews found
No relevant Reddit discussions about Mailerr’s performance or deliverability were found during research.
G2: No reviews found
No relevant Reddit discussions about Mailerr’s performance or deliverability were found during research.
Mailerr Pros
🟢 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.
🟢 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.
Mailerr Cons
🔴 High cost & extra fees: per‑mailbox pricing of $3.6–$4 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.
🔴 Limited analytics: while it monitors blacklists and spam reports, it lacks campaign‑level reporting and deliverability analytics.
Maildoso Review
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%.
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%.
Rating & Reviews
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?
"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?
Maildoso Pros
🟢 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.
🟢 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.
Maildoso Cons
🔴 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.
🔴 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.
Detailed Pricing Comparison
Mailbox type
Price per mailbox
Minimum package
Maildoso SMTP
$0.49-2.5
$25
Maildoso GW
$2.7-4
$40
Mailerr
$3.6-4
$40
Feature Comparison Table
Feature
Maildoso
Mailerr
Mailbox types
SMTP, GW
SMTP
API Availability
Full access (on all plans)
No access
IP type
IP rotation (best for deliverability)
US-based IP
Self-healing mailboxes
Support
Email, Chat, Slack, Tech Audits
Not specified
Refund policy
30-day guarantee
Strictly no refunds
Trials
300 mailboxes for 30 days
Not specified
Final rating
⭐⭐⭐⭐⭐
⭐
The True Cost of Bad Deliverability
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:
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.
- 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.
Final Thoughts
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.
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.
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.
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.
FAQ
- Q:Which provider has better deliverability?A:Mailerr leverages dedicated US IPs and custom tracking domains, which helps maintain reputation. Maildoso uses rotating IPs and self‑healing mailboxes. Deliverability depends on send volume, warm‑up strategy and content. Small teeams seeking predictability may prefer Mailerr’s dedicated IPs, while high‑scale senders benefit from Maildoso’s rotation.
- Q:Can I use my own domains?A:Both providers allow you to connect existing domains (or to register new ones – with Maildoso, you can do that for free).
- Q:What are the sending volume recommendations?A:Mailerr recommends sending up to 50 emails per day, which is extremely high and can lead to all your domains burning out simultaneously. Our tests show that by sending no more than 15 emails per day, your mailboxes remain healthy for months rather than weeks.
- Q:Can I mix Google Workspace and SMTP accounts?A:Yes, Maildoso offers Combo plans that allow you to seamlessly blend Google Workspace and SMTP accounts to balance deliverability and volume. Mailerr only offered SMTP mailboxes.
Related articles
Most cold emails fail simply because they land in spam. People never even see your offer. Our SMTP and Google Workspace mailboxes are built specifically for outbound; this means your emails will finally be seen, and you’ll start getting more positive replies.
Boost your outbound with our infrastructure!
BacklinkSwappers, inc.
1390 Market Street
Suite 200
San Francisco, CA 94102
1390 Market Street
Suite 200
San Francisco, CA 94102
Company
Legal
Product
Resources
