Anthropic uses Iterable for marketing email and SendGrid for transactional/notifications. They rank #782 in the Tranco list of most-popular domains. We've also observed sends via 3 other providers: Amazon SES, Postmark, HubSpot. Email goes out from 4 different subdomains. Their email authentication setup is solid (score 85/100). We've recorded 16 ESP changes since first observing this brand.
Non-ESP tools detected in this brand's emails. Independent of who sends — a brand can use any combination.
| HTML builder |
Authentication 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 10 emails we've observed. DMARC policy is read live from DNS.
DMARC reports sent to cloudflare.net. Policy
p=reject means receivers actively block or quarantine spoofed mail.
SPF alignment: 69% of observed emails use an aligned return-path (em9672.mail.anthropic.com, bounce.mail.anthropic.com, pm-bounces.mail.anthropic.com); the rest use third-party paths (amazonses.com, kilo.health, bf02x.hubspotemail.net) where DMARC has to rely on DKIM alignment.
DKIM alignment: all 292 observed emails sign with a domain aligned with anthropic.com (mail.anthropic.com, anthropic.com, research.anthropic.com). DKIM authenticates the visible From — supports DMARC directly.
TLS: modern — 98% TLS 1.3 (across 175 sends).
Delivery: fast — 100% of emails in the last 7 days arrive in under 10 seconds (across 61 sends).
Brands often use multiple ESPs (e.g. one for marketing, another for transactional/notifications).
Amazon SES 77 Postmark 9 HubSpot 5ESPs 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: anthropic.com, em9672.mail.anthropic.com, em7025.anthropic.com, bounce.mail.anthropic.com, kilo.health, transactional.hubspotemail.net, pm-bounces.mail.anthropic.com, bf02x.hubspotemail.net, amazonses.com, lumination.ai, collab360marketing.com, themathergroupllc.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 | 320 | 98.2% |
| promotions | 6 | 1.8% |
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 % |
|---|---|---|---|---|---|
| SendGrid | 144 | 97.2% | 2.8% | 0.0% | |
| Iterable | 93 | 97.8% | 2.2% | 0.0% | |
| Amazon SES | 58 | 100.0% | 0.0% | 0.0% | |
| HubSpot | 5 | 100.0% | 0.0% | 0.0% | |
| Postmark | 9 | 100.0% | 0.0% | 0.0% |
Weekly 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 anthropic.com has been observed sending from, and where their mail landed in Gmail.
| IP | Hostname | Obs | Placement | Reputation |
|---|---|---|---|---|
| 149.72.89.246 | o1.ptr3998.mail.anthropic.com |
45 | 8 | Check → |
| 168.245.100.91 | o6.ptr4169.mail.anthropic.com |
44 | 13 | Check → |
| 168.245.101.254 | o7.ptr8284.mail.anthropic.com |
36 | 10 | Check → |
| 168.245.101.31 | o8.ptr6101.mail.anthropic.com |
28 | 3 | Check → |
| 54.240.42.185 | a42-185.smtp-out.amazonses.com |
26 | 2 | Check → |
| 54.240.61.167 | a61-167.smtp-out.us-west-2.amazonses.com |
24 | 2 | Check → |
| 54.240.42.184 | a42-184.smtp-out.amazonses.com |
19 | 2 | Check → |
| 54.240.79.109 | a79-109.smtp-out.amazonses.com |
5 | 1 | Check → |
| 76.223.141.201 | c141-201.smtp-out.amazonses.com |
5 | 3 | Check → |
| 167.89.54.47 | o1.em2316.skilljar.com |
4 | 1 | Check → |
| 54.240.78.98 | a78-98.smtp-out.amazonses.com |
4 | 1 | Check → |
| 54.240.61.166 | a61-166.smtp-out.us-west-2.amazonses.com |
3 | — | Check → |
| 158.247.18.225 | bid46q7.bf02x.hubspotemail.net |
3 | — | Check → |
| 54.240.73.50 | a73-50.smtp-out.amazonses.com |
3 | — | Check → |
| 54.240.78.90 | a78-90.smtp-out.amazonses.com |
3 | — | Check → |
| 54.240.78.97 | a78-97.smtp-out.amazonses.com |
3 | 3 | Check → |
| 104.245.209.212 | mta212a-ord.mtasv.net |
2 | — | Check → |
| 50.31.205.11 | mta11-ab1.mtasv.net |
2 | — | Check → |
| 54.240.79.116 | a79-116.smtp-out.amazonses.com |
2 | — | Check → |
| 54.240.79.137 | a79-137.smtp-out.amazonses.com |
2 | — | Check → |
| 76.223.141.226 | c141-226.smtp-out.amazonses.com |
2 | — | Check → |
| 54.240.79.4 | a79-4.smtp-out.amazonses.com |
2 | — | Check → |
| 54.240.78.79 | a78-79.smtp-out.amazonses.com |
2 | — | Check → |
| 54.240.78.82 | a78-82.smtp-out.amazonses.com |
2 | — | Check → |
| 76.223.141.211 | c141-211.smtp-out.amazonses.com |
2 | — | Check → |
