| Date | IP Address |
| 2019-06-17 | 31.7.3.37 (ClassC) |
| 2025-07-14 | 172.67.162.124 (ClassC) |
| 2026-02-15 | 104.21.49.121 (ClassC) |
| Date | Domain | IP |
| smtp01.werkendleren.nl | 2025-01-12 | 104.21.49.121 |
| relay1.werkendleren.nl | 2025-01-06 | 104.21.49.121 |
| mail12.werkendleren.nl | 2025-02-12 | 172.67.162.124 |
| relay2.werkendleren.nl | 2025-05-09 | 104.21.49.121 |
| mail4.werkendleren.nl | 2025-04-20 | 104.21.49.121 |
| mail7.werkendleren.nl | 2025-08-08 | 104.21.49.121 |
| mta.werkendleren.nl | 2025-02-11 | 104.21.49.121 |
| mailgate.werkendleren.nl | 2026-01-29 | 172.67.162.124 |
| newmail.werkendleren.nl | 2025-06-03 | 172.67.162.124 |
| spam.werkendleren.nl | 2025-04-06 | 104.21.49.121 |
| mailin.werkendleren.nl | 2025-04-28 | 104.21.49.121 |
| authsmtp.werkendleren.nl | 2025-01-27 | 172.67.162.124 |
| postmaster.werkendleren.nl | 2025-05-08 | 104.21.49.121 |
| www.werkendleren.nl | 2025-07-14 | 172.67.162.124 |
| mx.werkendleren.nl | 2024-12-17 | 104.21.49.121 |
| a.mx.werkendleren.nl | 2025-03-22 | 104.21.49.121 |