Justworks uses Constant Contact for marketing email and SendGrid for transactional/notifications. They rank #19,892 in the Tranco list of most-popular domains. We've also observed sends via Customer.io. Their email authentication setup is solid (score 95/100). We've recorded 9 ESP changes since first observing this brand.
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 fdmarc.net. Policy
p=quarantine means receivers actively block or quarantine spoofed mail.
SPF alignment: 38% of observed emails use an aligned return-path (em6015.justworks.com, em2977.justworks.com, cio98787.justworks.com); the rest use third-party paths (amazonses.com) where DMARC has to rely on DKIM alignment.
DKIM alignment: 82% of observed emails sign with an aligned DKIM key (justworks.com, cio98787.justworks.com); the rest sign with third-party keys (zendesk.com) where DMARC has to rely on SPF alignment.
VMC issued by: entrust.
TLS: modern — 95% TLS 1.3 (across 56 sends).
Delivery (last 7 days): 46% under 10 seconds, 11% over 1 minute (across 37 sends).
Brands often use multiple ESPs (e.g. one for marketing, another for transactional/notifications).
Zendesk 42 Customer.io 12ESPs 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: justworks.com, mail.okta.justworks.com, amazonses.com, cio98787.justworks.com, em6015.justworks.com, em2977.justworks.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 | 194 | 100.0% |
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 % |
|---|---|---|---|---|---|
| Constant Contact | 99 | 100.0% | 0.0% | 0.0% | |
| Customer.io | 12 | 100.0% | 0.0% | 0.0% | |
| SendGrid | 25 | 100.0% | 0.0% | 0.0% | |
| Zendesk | 32 | 100.0% | 0.0% | 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 justworks.com has been observed sending from, and where their mail landed in Gmail.
| IP | Hostname | Obs | Placement | Reputation |
|---|---|---|---|---|
| 149.72.89.165 | wrqvrwxr.outbound-mail.sendgrid.net |
47 | 6 | Check → |
| 149.72.72.168 | wrqvqvxv.outbound-mail.sendgrid.net |
20 | 5 | Check → |
| 54.240.9.20 | a9-20.smtp-out.amazonses.com |
11 | — | Check → |
| 192.161.152.45 | mta-out15.pod27.use2.zdsys.com |
10 | — | Check → |
| 192.161.152.39 | mta-out9.pod27.use2.zdsys.com |
9 | — | Check → |
| 54.240.9.16 | a9-16.smtp-out.amazonses.com |
8 | 1 | Check → |
| 159.112.241.115 | v5115.v5c4dda55.use4.send.mailgun.net |
8 | — | Check → |
| 54.240.9.7 | a9-7.smtp-out.amazonses.com |
7 | — | Check → |
| 54.240.9.6 | a9-6.smtp-out.amazonses.com |
6 | 2 | Check → |
| 54.240.9.10 | a9-10.smtp-out.amazonses.com |
5 | 2 | Check → |
| 54.240.9.23 | a9-23.smtp-out.amazonses.com |
4 | — | Check → |
| 159.112.241.119 | v5119.v5c4dda55.use4.send.mailgun.net |
4 | — | Check → |
| 54.240.9.25 | a9-25.smtp-out.amazonses.com |
4 | — | Check → |
| 54.240.9.44 | a9-44.smtp-out.amazonses.com |
4 | 2 | Check → |
| 54.240.9.17 | a9-17.smtp-out.amazonses.com |
4 | 1 | Check → |
| 192.161.152.42 | mta-out12.pod27.use2.zdsys.com |
4 | 1 | Check → |
| 192.161.152.37 | mta-out7.pod27.use2.zdsys.com |
4 | — | Check → |
| 54.240.9.24 | a9-24.smtp-out.amazonses.com |
4 | — | Check → |
| 54.240.10.10 | a10-10.smtp-out.amazonses.com |
3 | 1 | Check → |
| 192.161.152.32 | mta-out2.pod27.use2.zdsys.com |
3 | — | Check → |
| 54.240.9.108 | a9-108.smtp-out.amazonses.com |
3 | — | Check → |
| 192.161.152.35 | mta-out5.pod27.use2.zdsys.com |
3 | — | Check → |
| 54.240.9.68 | a9-68.smtp-out.amazonses.com |
3 | — | Check → |
| 54.240.10.132 | a10-132.smtp-out.amazonses.com |
3 | — | Check → |
| 54.240.9.19 | a9-19.smtp-out.amazonses.com |
3 | — | Check → |
| Domain | ESPs detected | Delivery (7d) |
|---|---|---|
justworks.com | Constant Contact 133 Zendesk 42 SendGrid 26 Customer.io 12 |
