| Date | IP Address |
| 2014-06-06 | 66.6.40.74 (ClassC) |
| 2014-06-08 | 66.6.40.76 (ClassC) |
| 2014-06-15 | 66.6.40.81 (ClassC) |
| 2024-03-23 | 18.119.77.14 (ClassC) |
| 2024-07-25 | 3.138.227.8 (ClassC) |
| 2024-10-02 | 18.219.17.53 (ClassC) |
| 2024-10-25 | 3.139.193.180 (ClassC) |
| 2024-12-29 | 18.116.147.103 (ClassC) |
| 2025-04-14 | 3.143.79.102 (ClassC) |
| 2025-05-23 | 3.16.33.24 (ClassC) |
| 2025-07-03 | 3.137.85.179 (ClassC) |
| 2025-07-27 | 18.118.190.3 (ClassC) |
| 2025-08-10 | 3.134.150.38 (ClassC) |
| 2025-09-06 | 3.148.77.165 (ClassC) |
| 2025-09-13 | 3.132.243.131 (ClassC) |
| 2025-10-16 | 18.219.11.187 (ClassC) |
| 2025-11-02 | 18.221.92.244 (ClassC) |
| 2025-11-23 | 3.134.236.143 (ClassC) |
| Date | Domain | IP |
| 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 | 2025-11-03 | 50.31.156.110 |
| www.postmarkapp.com | 2023-10-04 | 3.138.237.220 |