A good Gmail result tells you very little about Outlook. Microsoft scores mail on its own signals, and a lot of B2B prospects sit on Microsoft 365. So we tested it on its own.
We ran two GlockApps seed tests. Every email was a real send from Deliveryman.ai infrastructure, not a simulation. Every Microsoft 365 seed landed in the inbox.
How GlockApps tests inbox placement
GlockApps sends your email to a list of real seed mailboxes at each provider, then reports where every copy landed: inbox, spam or missing. It is the closest thing to asking the mailbox provider directly, because it reads the actual result and not an estimate.
Test 1: Microsoft 365 landed 100% in the inbox
In our Microsoft 365 test, every seed mailbox received the email in the inbox. Not most of them. All of them.
Test 2: Gmail and Outlook in the inbox, Yahoo and AOL in spam
Our second GlockApps test covered a wider mix of providers. Gmail and Outlook landed in the inbox, and Google and Microsoft combined came in at 100%. Yahoo and AOL personal inboxes went to spam.
We are not great with Yahoo and AOL personal inboxes yet. We would rather tell you that than hide it.
Results at a glance
| Provider | Where it landed | GlockApps test |
|---|---|---|
| Microsoft 365 | 100% inbox, every seed | Test 1 |
| Outlook | Inbox | Test 2 |
| Gmail | Inbox | Test 2 |
| Yahoo (personal) | Spam | Test 2 |
| AOL (personal) | Spam | Test 2 |
What gets you into the Microsoft inbox
- Clean IP reputation. Our sending IPs had no blocklist hits. Barracuda, SpamAssassin and Proofpoint all rated the mail as not spam.
- A dedicated IP pool. Your mail goes out on infrastructure built for deliverability, so you do not need Google Workspace mailboxes to send.
- Authentication that passes. SPF, DKIM and DMARC have to be set up correctly. Microsoft began enforcing them for high-volume senders to Outlook.com consumer mailboxes in 2025.
Content and sending behavior still matter. A clean IP will not save a list full of bounces.
The full results are on our deliverability page.
