Email Service Providers (ESP) portfolio

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Catalogue of Email Service Providers (ESPs) — marketing automation, transactional and customer-engagement platforms — authorised via SPF on Tranco top-1M domains. This is the dedicated mailing-services view; see SaaS senders for non-ESP business apps and MX providers for inbound mail.

186ESPs in current scan
186catalogued (with description)
46.44%of SPF-domains use any ESP
2026-09-10scan date · 632,322 SPF domains

Catalogue coverage progress (target 90%)

100.0% of ESP-using SPF-volume is described (46.44% of all SPF-domains, out of 46.44% using any ESP). Uncatalogued senders are progressively added via the spf-classifier API + manual curation in dictionaries/saas_meta.py.
Zoho Campaigns (IN)
0.08%
ESP 🇮🇳 Asia-Pacific 507 domains
Zoho Campaigns India residency.
No historical data yet.
Zoho Campaigns (EU)
0.01%
ESP 🇪🇺 Europe 33 domains
Zoho Campaigns EU residency.
No historical data yet.

Maintain this catalogue programmatically

The same SPF classifier that builds /providers.html and /saas.html powers this page. To submit a batch of unknown SPF includes for tier 1-3 classification (heuristic → RDAP → web), POST to: 

POST https://<analyzer-host>:8090/classify
Content-Type: application/json

{"hosts": ["spf.example.com", "_spf.foo.io", "..."]}
→ returns batch_id; poll /batch/<id> for results + dict diff.

Confidence-≥0.8 RDAP/web matches are auto-promoted into PURE_ESP / GATEWAYS / FORWARDERS. Lower-confidence matches land in a shadow queue for human review before merging.

Source: OpenINTEL forward-DNS Tranco snapshot (2026-09-10). ESP patterns: dictionaries/esps.py. Descriptions: dictionaries/saas_meta.py. Sparklines render only for senders tracked in history.json; new ESPs will start appearing as future scans accumulate.