Google vs Microsoft vs SMTP Providers: Choosing the Right Infrastructure for Cold Email
Cold email isn’t just about good copy. It’s about your infrastructure—how your emails get sent, from where, and how likely they are to reach the inbox. In this post, we compare Google, Microsoft, and SMTP-based setups so you can build a smarter, more resilient email stack.
Google Email Infrastructure
Options: Direct Workspace | Educational/Legacy Panels |Reseller Accounts
Strengths:
High baseline trust with Gmail inboxes
Flexible for SMB and startup outreach
Easy access to free or low-cost inboxes (via panels or resellers)
Weaknesses:
Risk of shutdown if using educational or legacy panels
You can't control the IP — Google assigns it
Limited transparency into blacklist issues
When to use:
SMB to SMB outreach
SaaS to startup
Recommended Providers: Premium Inboxes, Puzzle Inboxes, F60tic, S-Mail
Microsoft Email Infrastructure
Options: Direct Office 365 | Azure Enterprise Mailboxes | SMTP through Azure IPs
Strengths:
High trust from Outlook/enterprise recipients
Microsoft IPs are typically strong and clean
Weaknesses:
UI and setup are complex
DNS/authentication setup less intuitive
When to use:
Targeting corporate or enterprise segments (legal, gov, finance)
Mid-market outreach requiring MSFT credibility
Recommended Providers: HyperTide, Thor’s Hammer, Superwave, MX-based setups
SMTP Infrastructure (The IP Matters Most Here)
SMTP refers to using your own or a third-party mail server to send emails. The critical difference among SMTP providers comes down to this:
Shared IP SMTP (High Risk)
You're sending emails through the same IP address as every other user on the platform. If one user sends spam or gets blacklisted, everyone suffers.
Poop-in-the-pool analogy: You might follow best practices, but someone else ruins the reputation, and you get penalized by association.
Platforms known for shared IPs:
Maildoso
Inframail
Mailscale
Mailforge
Risks:
Inconsistent inbox placement
Blacklist issues beyond your control
Dedicated IP SMTP (High Control)
You send from your own IP address, isolated from everyone else. Your reputation is solely based on your behavior.
Benefits:
Full control over sending quality
Easier to diagnose deliverability issues
More resilient to spam filter fluctuations
Platforms offering dedicated IPs:
Mission Inbox
Mailreef
Mailing.ai
Mission Inbox Bonus: Instead of tying you to a single IP, Mission Inbox gives you access to a pool of dedicated IPs that rotate. If one IP gets blacklisted, it's automatically removed from your pool and replaced—without you lifting a finger.
Risks:
If you're careless, you can still burn your own IP
Dedicated IPs must be warmed up properly
Which Should You Use?
Don't pick just one—blend them.
Use Gmail for SMB and startup targeting
Use Microsoft for enterprise recipients
Use SMTP (dedicated IP only!) to diversify and control your sending reputation
Benchmark each provider across:
Deliverability rates
Spam placement (use inbox placement tools)
Reply and conversion rates
Avoid shared IP SMTP providers unless you’re just testing volume. Long-term, it’s not worth the deliverability risk.
Final Thoughts: Control Your Deliverability, Don’t Gamble It
The infrastructure you choose will either make or break your cold email program. If you want stable results, you need to:
Know which providers use shared vs. dedicated IPs
Diversify your infrastructure mix
Monitor inbox placement regularly
Use this guide to start running experiments. Try Gmail to Gmail. Microsoft to enterprise. Dedicated IP SMTP to test performance.
And if you want to skip the guessing game? Mission Inbox gives you a clean, dedicated, auto-managed IP pool with built-in monitoring—so you can focus on results, not root causes.
