Duolingo uses Amazon SES as their primary email service provider. They rank #452 in the Tranco list of most-popular domains. Their email authentication setup is solid (score 100/100).
Amazon SESAuthentication signals observed in this brand's emails. SPF, DKIM and DMARC are the standard sender-authentication stack — see the DMARC policy below for whether spoofing is actually blocked or just monitored. One-click unsubscribe meets Google & Yahoo's bulk-sender requirements.
SPF / DKIM / DMARC above reflect the last 6 emails we've observed. DMARC policy is read live from DNS.
DMARC reports sent to Postmark DMARC. Policy
p=reject means receivers actively block or quarantine spoofed mail.
SPF alignment: all 11 observed emails use a return-path aligned with duolingo.com (bounces.duolingo.com). SPF authenticates the visible From — supports DMARC directly.
DKIM alignment: all 11 observed emails sign with a domain aligned with duolingo.com (duolingo.com). DKIM authenticates the visible From — supports DMARC directly.
VMC issued by: digicert.
Delivery: fast — 100% of emails in the last 7 days arrive in under 10 seconds (across 4 sends).
Brands often use multiple ESPs (e.g. one for marketing, another for transactional/notifications).
None — only the primary ESP(s) shown aboveESPs we've seen sending email for this brand. Green = confirmed by SPF, sender IP rDNS, or known infra pairing (label shows the source). Grey = observed but not yet confirmed by SPF or PTR.
ESPs this brand has authorized in their SPF record. We confirm them with a green ✓ only after seeing recurring use (3+ emails across 2+ days). Until then they stay here — either we haven't observed any email yet, or we've seen a handful but not enough to call them a regular sender for the brand.
Probed: duolingo.com, bounces.duolingo.com
Folder distribution across all emails from this brand observed in Gmail inboxes. High inbox % = good deliverability; spam appearances are the headline signal.
| Folder | Count | Share |
|---|---|---|
| inbox | 8 | 88.9% |
| promotions | 1 | 11.1% |
Placement observed in Outlook / Microsoft 365 mailboxes. Focused Inbox splits mail into two tabs, "Focused" (inbox) and "Other", plus Junk. 50% reached the Focused inbox across 4 observed emails.
Which ESP's emails are landing where. Sorted by spam % so problem senders surface first. Brands using one ESP for marketing and another for transactional often see very different placement profiles per ESP. Per-ESP folder data only started being captured recently — counts here may be smaller than the total above until backfill catches up.
| ESP | Emails | Placement | Inbox % | Tabs % | Spam % |
|---|---|---|---|---|---|
| Amazon SES | 7 | 85.7% | 14.3% | 0.0% |
Daily observations per ESP. Brands often run multiple ESPs concurrently — marketing on one, transactional on another — so this chart shows usage rather than switches.
IP addresses duolingo.com has been observed sending from, and where their mail landed in Gmail.
| IP | Hostname | Obs | Placement | Reputation |
|---|---|---|---|---|
| 54.240.30.74 | a30-74.smtp-out.amazonses.com |
1 | — | Check → |
| 76.223.138.217 | c138-217.smtp-out.amazonses.com |
1 | — | Check → |
| 76.223.138.200 | c138-200.smtp-out.amazonses.com |
1 | — | Check → |
| 54.240.48.206 | a48-206.smtp-out.amazonses.com |
1 | — | Check → |
| 54.240.69.11 | a69-11.smtp-out.amazonses.com |
1 | — | Check → |
| 54.240.69.33 | a69-33.smtp-out.amazonses.com |
1 | — | Check → |
| 54.240.69.24 | a69-24.smtp-out.amazonses.com |
1 | — | Check → |
| 76.223.138.215 | unknown |
1 | — | Check → |
| 54.240.69.23 | unknown |
1 | — | Check → |
| 54.240.69.8 | a69-8.smtp-out.amazonses.com |
1 | 1 | Check → |
| 54.240.10.32 | a10-32.smtp-out.amazonses.com |
1 | 1 | Check → |
| 76.223.138.214 | unknown |
1 | — | Check → |
| 54.240.69.36 | unknown |
1 | — | Check → |
| Domain | ESPs detected | Delivery (7d) |
|---|---|---|
duolingo.com | Amazon SES 15 |
