How long does it take to build sender reputation?
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One to four weeks is the typical timeframe, but that's assuming you do everything right. The actual answer depends on whether you're warming a new IP address, a new domain, or both.
IP reputation builds faster because mailbox providers track IPs more aggressively. If you're on a dedicated IP at a place like SendGrid or Mailgun, you can build a decent reputation in 7-10 days if you follow a proper warmup schedule (starting at 50-100 emails on day one, doubling daily, keeping engagement high). Shared IPs don't need warming because the provider already maintains the reputation.
Domain reputation takes longer because it's tied to your brand's entire sending history. A brand new domain might need 2-4 weeks of consistent, clean sending before Gmail and Outlook fully trust it. If you're moving from an old domain to a new one, you're essentially starting from zero.
What mailbox providers actually watch during this period: bounce rates (anything over 3% is bad), spam complaint rates (keep it under 0.1%), engagement (opens, clicks, replies), and consistency (wild volume swings are red flags). They're also checking that your authentication is set up correctly. If your SPF, DKIM, and DMARC aren't in place before you start warming, you're wasting time.
The biggest mistake people make is jumping straight to high volume. Sending 50,000 emails on day one from a new domain or IP will land you in spam immediately, and recovering from that can take months. The second biggest mistake is sending to your entire list without segmenting by engagement first. Start with your most engaged subscribers (people who opened in the last 30 days), then expand to less engaged segments as your reputation improves.
You'll know it's working when your inbox placement starts climbing. Check your analytics after the first week. If you're seeing 80%+ inbox rate with low bounces and complaints, you're on track. If you're stuck at 50% or lower, something's wrong (probably list quality or content). You can check if you've been blocklisted or ask us for help if you're stuck.
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