What’s Microsoft’s reputation decay speed?
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Microsoft Outlook's reputation system punishes bad behavior fast and rewards good behavior slowly. A spam complaint spike or sending to traps can crater your reputation within days. Recovery takes weeks of clean behavior. This imbalance is why Microsoft is the one ISP that scares most senders the most.
Why the speed asymmetry matters. Microsoft's systems treat emerging threats seriously. A sudden complaint spike looks like a botnet attack or compromised list in their eyes. They lock down your sending immediately. It's overly cautious by design. Once they perceive a threat, you're in the penalty box. Months of good sending history gets overridden by one bad campaign. This is the opposite of how some providers work (Gmail gives you more benefit of the doubt).
Recovery timeline reality. If you're currently below Microsoft's junk threshold, you'll stay in the inbox as long as you keep your metrics clean. Bounce rate under 5 percent. Complaint rate under 0.1 percent. Authentication passing. No traps. One bad campaign that spikes your complaints to 0.5 percent lands you in junk. Now you're looking at 2-4 weeks of sustained good behavior to climb back to inbox. Every day of bad sending extends the recovery. It's not linear.
What to do immediately if reputation drops. Check SNDS (Sender Network Data Service) to see your current status. Reduce send volume by at least 50 percent immediately. Review your list for quality issues (old addresses, unengaged subscribers, purchased list quality). Fix your SPF and DKIM if they've drifted. Stop any automated campaigns so you can audit them. Run through your authentication records again. Then slowly increase volume over a week as metrics stabilize.
Prevention is cheaper than recovery. The real lesson here. Monitor your metrics constantly. Set alerts that fire when your complaint rate hits 0.15 percent or your bounce rate hits 4 percent. Catch the problem at the warning stage before Microsoft locks you down.
Start with how to read SNDS data and Microsoft reputation recovery timeline. These guide you through the numbers and the path forward if you're already in trouble.
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