It all depends on your account type which in turn depends on your activity. You can understand the dynamics of the restrictions on your account from the following table:
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
Thank you for this also. Will help a lot to get where I need to be and not have to worry about posting restrictions and get my rank up and become a good member of the community.