Thanks for this question and the reply. Pls can you clarify the time interval?
It is 360 seconds (6 minutes) for newbies. This restriction is reduced as the user will increase in rank. You can see this theymos post about it which I think has not changed till now.
I've adjusted the limits to make spamming more difficult.
| Activity | Min. seconds between post actions | Max PM recipients | PMs per hour |
| 0 | 360 | 3 | 5 |
| 16 | 74 | 5 | 30 |
| 30 | 60 | 5 | 60 |
| 60 | 30 | 5 | 60 |
| 100 | 12 | 10 | 120 |
| 200 | 10 | 15 | 120 |
| 300 | 8 | 20 | 120 |