Inframail review after 6 months. Unlimited Microsoft inboxes sounds great until you try it

infra_honest · 2026-03-20 · 2,340 views

I signed up for Inframail because unlimited Microsoft 365 inboxes at a flat rate sounded like the best deal in cold email. Six months later, here is my honest review of what worked, what didn't, and why I ended up switching.

What Inframail offers: Unlimited Microsoft 365 inboxes for a flat monthly fee. You set up as many accounts as you want across your domains. No per-inbox pricing. For agencies running 100+ inboxes, the math looks incredible compared to per-inbox providers.

What worked: The onboarding was smooth. I had 40 inboxes set up within a couple of days. DNS was configured (SPF, DKIM, DMARC all passing). The flat rate pricing genuinely saved money at my volume. If you need 80 or 100 Microsoft inboxes, paying per-inbox would cost significantly more.

What didn't work:

Microsoft only, no Google. This is the biggest limitation. About 30 to 35% of B2B email addresses are on Gmail. Sending from Outlook to Gmail recipients consistently underperforms compared to sending Google to Google. My reply rates to Gmail prospects were 25 to 30% lower than to Outlook prospects. That gap adds up fast when a third of your prospect list is on Gmail.

No pre-warming. Every inbox arrived fresh with zero sending history. I had to warm all 40 accounts myself using Instantly's warmup. That took 14 to 21 days before I could safely send cold emails. On a flat-rate model, those 2 to 3 weeks of warmup time feel expensive because you're paying for inboxes you can't use yet.

Deliverability inconsistencies. Some of my inboxes performed great. 85%+ inbox placement. Others on the same domain with the same DNS configuration sat at 60 to 65% inbox placement after a month of warming. I could never pin down why. Inframail support said it was normal variance, but a 20+ percentage point gap between inboxes on the same domain is not normal in my experience.

Support response times. Email only support. Average response time was 12 to 24 hours. When you have deliverability issues, 24 hours feels like a week. I missed a full day of sending once because I was waiting for a response about a DNS issue that turned out to be a simple fix.

Why I switched to PuzzleInbox: I moved to PuzzleInbox for the dual-platform approach. Google Workspace AND Outlook. Pre-warmed accounts that arrive ready to send. WhatsApp support that responds in minutes, not hours. My overall reply rate went up about 20% after the switch because I could finally match sender platform to recipient platform. Gmail prospects got emails from Google Workspace accounts. Outlook prospects got emails from Outlook accounts. That platform diversification made a measurable difference.

Who Inframail still makes sense for: If you need 100+ Microsoft inboxes at the absolute lowest cost per inbox and you're comfortable with Microsoft-only deliverability, Inframail's flat rate model saves real money. Agencies doing pure volume plays on Microsoft infrastructure can make it work. But if deliverability matters more than cost (and it should), the dual-platform approach with pre-warmed inboxes from PuzzleInbox produces better results even at a higher per-inbox price.