| Date | IP Address |
| 2023-08-16 | 3.137.63.180 (ClassC) |
| 2024-03-23 | 52.15.63.207 (ClassC) |
| 2024-05-12 | 3.140.102.107 (ClassC) |
| 2024-06-09 | 3.16.0.172 (ClassC) |
| 2024-08-06 | 3.22.14.241 (ClassC) |
| 2024-12-03 | 3.14.159.59 (ClassC) |
| 2025-04-09 | 3.16.84.146 (ClassC) |
| 2025-04-19 | 3.147.162.186 (ClassC) |
| 2025-06-23 | 18.216.136.205 (ClassC) |
| 2025-07-03 | 3.14.0.242 (ClassC) |
| 2025-08-24 | 18.224.36.243 (ClassC) |
| 2025-09-06 | 3.19.196.195 (ClassC) |
| 2025-10-13 | 3.23.90.99 (ClassC) |
| 2025-12-02 | 3.15.121.205 (ClassC) |
| 2025-12-02 | 52.14.238.71 (ClassC) |
| 2025-12-31 | 18.191.14.132 (ClassC) |
| Date | Domain | IP |
| ingress-proxy-marketing-us-east-2.postmarkapp.com | 2025-11-26 | 3.151.126.85 |
| assets-useast2.postmarkapp.com | 2021-11-19 | 99.84.64.22 |
| rebound.postmarkapp.com | 2023-10-04 | 3.14.57.40 |
| rwd.postmarkapp.com | 2025-10-12 | 161.35.235.194 |
| blog.postmarkapp.com | 2014-06-06 | 66.6.40.74 |
| sg.postmarkapp.com | 2024-11-24 | 18.224.119.155 |
| api.postmarkapp.com | 2023-08-16 | 3.137.63.180 |
| fyi.postmarkapp.com | 2025-11-09 | 3.130.2.125 |
| spamcheck.postmarkapp.com | 2024-01-11 | 3.136.198.246 |
| assets.postmarkapp.com | 2024-07-22 | 99.84.66.66 |
| public-assets.postmarkapp.com | 2025-10-13 | 50.31.156.110 |
| craft-assets.postmarkapp.com | 2025-03-09 | 3.163.189.111 |
| status.postmarkapp.com | 2025-08-10 | 146.75.41.91 |
| account.postmarkapp.com | 2024-05-09 | 3.137.63.19 |
| support.postmarkapp.com | 2024-07-12 | 18.216.16.253 |
| public-assets-dev.postmarkapp.com | 2025-11-26 | 50.31.156.110 |
| www.postmarkapp.com | 2023-10-04 | 3.138.237.220 |