On3 uses Sailthru as their primary email service provider. They rank #5,636 in the Tranco list of most-popular domains. Their email authentication setup is solid (score 88/100). Missing: DMARC enforcement.
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.
DMARC reports sent to on3.com. Policy
p=none is monitor-only — receivers won't act on spoofing yet.
SPF alignment: observed emails use a third-party return-path (mx.sailthru.com) — SPF passes there but doesn't align with on3.com, so DMARC has to rely on DKIM alignment.
DKIM alignment: all 3 observed emails sign with a domain aligned with on3.com (newsletter.on3.com). DKIM authenticates the visible From — supports DMARC directly.
VMC issued by: entrust.
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: on3.com, mx.sailthru.com, newsletter.on3.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 | 3 | 23.1% |
| promotions | 10 | 76.9% |
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 % |
|---|---|---|---|---|---|
| Sailthru | 10 | 30.0% | 70.0% | 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 on3.com has been observed sending from, and where their mail landed in Gmail.
| IP | Hostname | Obs | Reputation |
|---|---|---|---|
| 192.64.236.192 | mta236-192.sailthru.com |
2 | Check → |
| 192.64.236.176 | mta236-176.sailthru.com |
2 | Check → |
| 192.64.236.187 | mta236-187.sailthru.com |
1 | Check → |
| 192.64.236.185 | mta236-185.sailthru.com |
1 | Check → |
| 192.64.237.215 | pmta22.sailthru.com |
1 | Check → |
| 192.64.237.212 | pmta19.sailthru.com |
1 | Check → |
| 192.64.236.15 | mta236-15.sailthru.com |
1 | Check → |
| 192.64.236.251 | mta236-251.sailthru.com |
1 | Check → |
| 192.64.236.13 | mta236-13.sailthru.com |
1 | Check → |
| 192.64.237.234 | mta237-234.sailthru.com |
1 | Check → |
| 192.64.237.41 | mta237-41.sailthru.com |
1 | Check → |
Per-IP inbox / promotions / spam is being collected and will appear here as new emails are observed.
| Domain | ESPs detected | Delivery (7d) |
|---|---|---|
newsletter.on3.com | Sailthru 13 |
