MailDeck has an interesting pricing model — per-domain instead of per-inbox, with up to 100 inboxes per domain. At their Outlook Normal tier, the per-inbox math can get very low. On paper, it's one of the cheapest options in the market.
But we've worked with agencies who've tried the high-density domain approach, and there's a reason most infrastructure providers cap at 2-3 inboxes per domain. Packing 100 inboxes on a single domain concentrates risk. One domain reputation hit takes down all 100 inboxes simultaneously.
If you're evaluating MailDeck or already using it and want to understand the tradeoffs, here's an honest breakdown from someone managing 217,600+ inboxes at ScaledMail.
Why People Look for MailDeck Alternatives
MailDeck has carved out a niche with per-domain pricing and high inbox density. The per-domain model makes the entry point attractive at scale. But the model has real limitations:
- 100 inboxes per domain concentrates risk. Email providers evaluate reputation at the domain level. If one inbox on a domain gets flagged, it impacts every other inbox on that same domain. With 100 inboxes per domain, a single spam complaint can cascade across your entire operation on that domain. Standard practice is 2-3 inboxes per domain on Google Workspace, and while Microsoft 365 can handle more density under expert management, 100 is well beyond what any experienced operator would recommend.
- Per-domain pricing is confusing at scale. Outlook Normal at $30/domain, Premium at $40/domain, different tiers for different features. The volume calculator helps, but when you're comparing to per-inbox providers, the math gets complicated fast. Simple pricing matters when you're scaling.
- Promotional pricing may not last. MailDeck periodically runs sales and discounts. Building your infrastructure budget on promotional pricing is risky — your costs need to be predictable month over month. Make sure you understand the standard rates before committing.
- "Diversified Stack" and "Pre-Warmed Inboxes" are new. MailDeck recently added these features. New features sound good in marketing copy, but they're unproven at scale. ScaledMail has offered multi-ESP infrastructure and pre-aged domains since day one — with 217,600+ inboxes of operational data behind them.
- No white-glove management. MailDeck is self-serve with a dashboard. When deliverability drops across one of your 100-inbox domains, you're diagnosing the problem yourself.
The Domain Density Problem
This deserves its own section because it's the core architectural difference.
Standard cold email best practice: 2-3 inboxes per domain on Google Workspace. On Microsoft 365, ScaledMail runs up to 25 inboxes per domain through our managed Azure tenant configuration — and even at 25, that's dramatically more conservative than MailDeck's 100. Self-managed M365 should stick to 2-3 per domain. The logic is simple — fewer inboxes per domain means less concentrated risk. If a domain gets flagged, you lose 2-25 inboxes, not 100. And plan for 30-50 cold emails per domain per day across all mailboxes on that domain — this is the volume ceiling that keeps you under ESP radar.
MailDeck's 100-inbox-per-domain model optimizes for a different thing: per-inbox cost. More inboxes on fewer domains = lower cost per inbox. But it creates a fragility problem. One bad campaign, one spam complaint wave, one ESP filter change that targets your domain — and 100 inboxes go down simultaneously.
We've seen this exact scenario play out. An agency running 50 inboxes across 2 domains (25 each) had one domain get spam-flagged after a list quality issue. They lost 25 inboxes overnight. If those 50 inboxes had been on one domain, they'd have lost everything.
There's also the Microsoft tenant block problem. At high inbox density — 49, 99, or 100 inboxes per domain — you're far more likely to trigger "unusual activity" blocks from Microsoft. These don't necessarily destroy your account or permanently damage your reputation, but you need to get them unblocked by interfacing with Microsoft support directly. That's tedious at best. You get downtime — minimum a day or two. For teams working with providers that aren't familiar with how to navigate Microsoft's support process, the downtime can be much longer. We've seen teams have to spin up entirely new infrastructure because they couldn't figure out how to get unblocked.
At ScaledMail's 25-per-domain Azure tenant configuration, we see these blocks far less frequently. And when they do happen, our team knows the process to resolve them — usually within hours, not days.
Diversification isn't just about ESPs. It's about domains too.
ScaledMail: Multi-ESP, Isolated, Managed
Conservative Inbox Density
We run 2-3 inboxes per domain on Google Workspace and manage Microsoft 365 density carefully based on operational data from 217,600+ inboxes. Every outreach domain forwards to your main business website — close enough to look legitimate, separate enough to protect your primary domain. More domains with fewer inboxes = more resilient infrastructure. It costs more per inbox, but it protects your campaigns.
Google Workspace + Microsoft 365 + SMTP
True ESP diversification. When Google tightens filters, your Microsoft inboxes keep running. When Microsoft cracks down, Google picks up the slack. MailDeck's "Diversified Stack" is new and unproven. ScaledMail's multi-ESP approach has years of operational data.
Pre-Aged Domains (Proven)
ScaledMail offers pre-aged domains — 30, 90, or 180 days old — with established sender reputation. Skip the warmup wait entirely. MailDeck recently introduced "Pre-Warmed Inboxes," but this is a new offering. Our pre-aged domain pipeline has been running long enough to have hundreds of domains in rotation at any given time.
Expert-Managed, Not Dashboard-Managed
Dedicated Slack + web chat + in-app chat — all routed to humans. Proactive monitoring that catches deliverability issues before they impact campaigns. We recommend maintaining a 2:1 warmup ratio permanently — for every 1 cold email, 2 warmup emails via your warmup tool. ScaledMail is compatible with all warmup tools; warmup is not included in our service, but we guide you on the right ratio and tools. We manage domain rotation on a 2-batch system so you always have fresh, healthy infrastructure.
Feature Comparison: ScaledMail vs MailDeck
| Feature | ScaledMail | MailDeck |
|---|---|---|
| Pricing model | Per-inbox, volume discounts | Per-domain (~100 inboxes/domain) |
| Inbox density | 2-3/domain (Google), managed density (M365) | Up to 100 inboxes per domain |
| ESP options | Google Workspace + Microsoft 365 + SMTP | Outlook + new "Diversified Stack" |
| Infrastructure isolation | Isolated tenants | Per-domain |
| Pre-aged domains | Established (30, 90, 180 day) | New "Pre-Warmed Inboxes" offering |
| DNS configuration | Fully managed by team | Self-serve with dashboard |
| Deliverability support | Dedicated Slack, human experts | Dashboard + self-serve |
| Domain rotation | Managed 2-batch rotation | Manual |
| Billing | Month-to-month, predictable pricing | Per-domain pricing |
Pricing Comparison
| Scenario | MailDeck | ScaledMail |
|---|---|---|
| 50 Outlook inboxes | ~1 domain, per-domain pricing | See current pricing |
| 200 inboxes | ~2 domains | Custom agency package |
| DNS setup | Self-serve (your time) | Included |
| Deliverability support | Not included | Included (humans in the loop) |
MailDeck's per-inbox math can win at scale with high-density domains. But 200 inboxes on 2 domains means a single domain issue takes out 100 inboxes at once. ScaledMail would spread 200 inboxes across 100 Google domains or manage Microsoft density conservatively — dramatically different risk profiles.
Who Should Stay with MailDeck
MailDeck is the right choice if:
- Per-inbox cost is the absolute primary driver and you're comfortable with high density
- You want Outlook-focused infrastructure specifically
- You have the technical skills to self-manage DNS, warmup, and deliverability
- You understand and accept the concentrated risk of 100 inboxes per domain
- You've confirmed the standard (non-promotional) pricing works for your budget
Who Should Switch to ScaledMail
ScaledMail is built for teams who:
- Need diversified infrastructure across Google and Microsoft
- Want conservative inbox density that protects against domain-level blowups
- Need proven pre-aged domains, not a new pre-warmed feature
- Value human expert management over dashboard self-serve
- Want predictable pricing that doesn't change with sale cycles
- Have experienced the cascading failure that comes from high-density domains
Making the Switch
- Infrastructure assessment: We review your current MailDeck setup, domain health, and volume needs
- Multi-ESP provisioning: Google Workspace + Microsoft 365 on isolated, conservatively-densified infrastructure
- DNS configured: SPF, DKIM, DMARC set up by our team
- Fast deployment: Pre-aged domains for same-week launch
- Ongoing management: Dedicated Slack, proactive monitoring, managed domain rotation
Frequently Asked Questions
Is MailDeck good for cold email?
MailDeck is a legitimate provider with competitive per-domain pricing. The main concerns are high inbox density per domain (concentrated risk), new and unproven diversification features, and self-serve management. For teams that want resilient, managed infrastructure with conservative density, ScaledMail is the better fit.
How much does MailDeck cost?
MailDeck charges per domain with tiers like Outlook Normal and Premium. Each domain supports up to 100 inboxes. Check their pricing page for current rates — they run periodic promotions, so confirm the standard pricing before budgeting. They also have a volume calculator.
Is 100 inboxes per domain safe for cold email?
It's technically possible but concentrates risk. Email providers evaluate reputation at the domain level. If one domain gets flagged, all 100 inboxes are affected simultaneously. Standard cold email best practice is 2-3 inboxes per domain to distribute risk. Higher density optimizes for cost at the expense of resilience.
What's the biggest difference between ScaledMail and MailDeck?
Risk architecture. MailDeck packs up to 100 inboxes per domain to minimize cost. ScaledMail uses conservative density across more domains to maximize deliverability resilience. The second difference is management: ScaledMail provides dedicated human expert support versus MailDeck's self-serve dashboard.
Can I migrate from MailDeck to ScaledMail?
Yes. We provision new inboxes on isolated infrastructure with conservative density, warm them or use pre-aged domains, and you swap into your sequencer. Run both during transition. Most migrations complete in 48-72 hours.
Get Started
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