ESP warmup for 98%+ inbox placement on Gmail and Outlook
Increase your email deliverability with specific providers.
Every major email provider
Whether you send from one inbox or a hundred, Warmupinbox plugs into the stack you already use.
Why use ESP warmup?
Most teams send to the same one or two inbox providers. Generic warmup spreads reputation thin across providers your prospects don't even use — ESP warmup concentrates the signal where it pays off.
Generic warmup spreads thin
Standard warmup distributes signal evenly across every provider, even ones your prospects don't use. That's wasted reputation.
Targeted warmup compounds
ESP warmup concentrates 80%+ of your warmup volume on the providers you send to most — Gmail, Workspace, Outlook, M365 — so reputation builds fastest where it matters.
Outcomes cold-email teams measure within 30 days
Inbox placement lift
Measured across Gmail, Outlook, and Yahoo after 30-day warmup.
Reply rate on cold sequences
More inboxes reached = more replies. Compounds week over week.
Spam flags on outbound
Fewer reports back to providers; sender reputation stops eroding.
Everything you need to dominate key providers
Prioritize key ESPs
Tell us where your prospects live. We weight warmup volume toward Gmail, Workspace, Outlook, M365, or any combination.
Dedicated domain strategy
Run separate sending domains per ESP to multiply inbox real estate. Multi-domain setups supported out of the box.
Per-provider scoring
See your sender reputation broken out by Gmail, Outlook, Yahoo, Workspace, and M365. Spot weak providers before they tank a campaign.
Network of 30,000+ real inboxes
Real accounts across every major provider, so we can over-index on the ones you care about without faking volume.
Smart routing
As reputation matures, the network shifts emphasis. New domain on Workspace? We start there. Already trusted on Gmail? More Outlook volume.
Provider-specific alerts
If reputation drops on a specific ESP, get pinged immediately so you can pause campaigns and investigate before it spreads.
Why our warmup network actually works
Real inboxes, real conversations, real reputation. Here's what's behind the 30,000+ number.
Real inboxes
Each inbox is a real account with real conversation history. No bots, no auto-generated personas.
Quality monitored
We audit the network weekly. Stale or low-engagement accounts are removed so reputation stays clean.
Diverse provider mix
Gmail, Outlook, Yahoo, Workspace, Microsoft 365, Zoho — reputation builds across every major provider.
30 of 30,000+ active accounts
Three steps to focused warmup
Sign up, pick your providers, activate. Sixty seconds end-to-end.
Choose your preferred ESPs
Pick the providers you send to most: Google Workspace, Outlook, Microsoft 365, Yahoo, or any mix.
Activate warmup
One click. Reputation builds on your chosen ESPs from day one.
Built for senders who live in the inbox
Lifecycle email that actually lives up to its name.
Nurture sequences, product updates, announcement blasts — warm sending domains means your carefully-written copy actually reaches the people you wrote it for.
Frequently asked questions
What is ESP warmup, and how is it different from regular email warmup?
Regular email warmup builds sender reputation evenly across every major provider. ESP warmup concentrates warmup volume on the specific providers your prospects use — typically Google Workspace and Outlook. Same mechanism, sharper aim.
Does this work if I send through SendGrid, Mailgun, or other sending platforms?
Yes. ESP warmup here refers to your receiving mailbox providers, not your sending platform. Whether you send through SendGrid, Mailgun, Postmark, or directly through Gmail or Outlook, we warm reputation between your sender and the inbox providers you target.
Should I run dedicated domains for different ESPs?
For high-volume cold outreach, yes. We recommend at minimum: one domain dedicated to Google Workspace prospects, one to Outlook/M365. Concentrating reputation per domain per ESP compounds faster than splitting one domain across all providers.
Which ESPs are supported?
Google Workspace, Gmail, Outlook, Microsoft 365, Yahoo, and Zoho. Tell us your provider mix at setup; we route warmup traffic accordingly.
How long until I see results?
Most teams see open-rate lifts within 14–21 days on their target ESP, with full warmup maturity at 45–60 days. Faster on established domains; slower on brand-new sending domains.
Land where your prospects already are
Stop spreading warmup thin. Concentrate reputation on the providers that move the needle.