Microsoft Outlook inboxes warm up differently than Google Workspace and if you treat them the same you will burn them
outlook_warm_vera · 2026-08-16 · 190 views
I run a split infrastructure. Half my inboxes are PuzzleInbox Google Workspace, half are Outlook 365 provisioned through PuzzleInbox. They behave very differently during warmup and most guides I've read treat them interchangeably. They are not interchangeable.
Google Workspace inboxes during warmup are relatively forgiving. You can hit 20 warmup emails per day within two weeks without seeing flags. The inbox reputation builds steadily on Google's own infrastructure, which already carries strong domain authority. By day 14, most of my Google Workspace inboxes pass GlockApps at 85 percent inbox placement or better on Gmail addresses.
Outlook inboxes are more sensitive at the start. Microsoft's spam filters evaluate new senders more aggressively in the first three weeks. I tried the same 14-day ramp schedule I use for Google Workspace and saw Outlook inbox placement sitting at 68 percent on day 14. Not good enough to start cold sends.
What works for Outlook: a slower ramp. Start at 5 warmup emails per day in week one. Ten in week two. Fifteen in week three. Do not push past 20 per day until week four. By week four, Outlook inbox placement on GlockApps consistently reads above 85 percent.
The other difference: Outlook inboxes are more sensitive to sudden volume spikes. I moved one Outlook inbox from 15 to 22 cold sends on the first day of a campaign. Google handles spikes like that without much complaint. The Outlook inbox got flagged and I spent three days nursing it back to normal placement. Now I ramp cold sends on Outlook more gradually than on Google, even after warmup ends.
If you are using PuzzleInbox for both inbox types, their WhatsApp support can tell you the specific warmup timeline they recommend for each provider. Build separate ramp schedules. It costs two extra weeks of patience. It saves you from burning inboxes that cost real money to replace.