| Date | IP Address |
| 2018-08-08 | 34.224.130.22 (ClassC) |
| 2023-10-04 | 3.14.57.40 (ClassC) |
| 2023-11-16 | 3.17.92.53 (ClassC) |
| 2024-01-10 | 3.18.85.53 (ClassC) |
| 2024-03-22 | 3.12.236.26 (ClassC) |
| 2024-03-23 | 3.139.153.130 (ClassC) |
| 2024-06-29 | 13.58.228.225 (ClassC) |
| 2024-07-23 | 3.12.245.253 (ClassC) |
| 2024-08-06 | 18.219.174.214 (ClassC) |
| 2024-10-23 | 18.119.79.129 (ClassC) |
| 2024-12-29 | 18.190.12.243 (ClassC) |
| 2025-04-08 | 18.222.37.7 (ClassC) |
| 2025-04-19 | 18.221.177.241 (ClassC) |
| 2025-07-16 | 3.128.167.43 (ClassC) |
| 2025-08-06 | 18.118.177.170 (ClassC) |
| 2025-08-29 | 3.142.128.151 (ClassC) |
| 2025-09-06 | 18.217.106.225 (ClassC) |
| 2025-09-09 | 3.130.232.205 (ClassC) |
| 2025-11-01 | 3.17.126.150 (ClassC) |
| 2026-01-03 | 3.151.67.240 (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 |