90% of your emails to Microsoft recipients never land.
Even if your copy is perfect. Even if your offer is great.
They just don't see it.
We cracked it 🧙
→ Watch the full Microsoft Deliverability Blueprint
Here's why this matters:
The bigger the company you're targeting, the more likely they use Microsoft.
- SMBs: 90% Google, 10% Microsoft
- Mid-market: 70/30
- Enterprise: Often 50/50 or Microsoft-heavy
If you're selling upmarket, you're losing half your pipeline due to the deliverability.
How we’ve cracked Microsoft’s Algo
15,000+ mailboxes managed. 300+ B2B teams.
Our clients get 5-12% reply rates on Microsoft-only audiences.

Here's the blueprint:
1. Analyze your ESP mix Use MX Toolbox (free) to see what % of your audience is on Microsoft.
2. Build separate infrastructure Microsoft needs its own setup. Don't mix it with Google.
3. Azure SMTP + Enterprise IP Not Google mailboxes. Not Outlook. Azure SMTP with enterprise-level IP.
4. The ratios
- 1 domain = 10 mailboxes
- 5 emails/day per mailbox
- That's 50 emails/day per domain
5. Premium warm-up Outlook-specific pools. 3 weeks minimum. Cheap warm-up = ruined deliverability.
6. Rotation buffer Keep 10-30% extra domains warming. When one burns, swap immediately.
7. Clean copy No links. No HTML. No tracking pixels. Plain text only.
8. Monitor the 96% threshold Inbox placement drops below 96%? Rotate that domain.
❌ Who this is NOT for:
If you're only targeting startups and SMBs, Google optimization is usually enough. Skip this.
✅ Who this IS for:
Anyone selling to mid-market or enterprise where Microsoft usage is 30%+. This is the difference between replies and radio silence.
Quick reminder:
We build and operate this infrastructure for B2B teams.
You own the ICP and copy. We own deliverability.
If you want us to handle this for you → book a call
— Ilya
Get sending infrastructure that stays out of spam
We build and run your cold email infrastructure: domains, mailboxes, daily placement checks and a rotation pool.
Ilya AzovtsevCo-founder
Co-founder of GrowthBand. Helped scale lemlist from $20k MRR to $10M ARR and built automation at Expandi; now runs the cold email infrastructure behind 32,000+ mailboxes.



