As a measure against spammers and scammers, we disallow sending PMs until you've posted enough, gained enough reputation, or been a member long enough to reach the rank of Community Member.
The requirements aren't stringent at all (15 rep points or 5 posts + 5 days), but it ensures that one can't simply join and send PMs right away.
deceptikon
Challenge Accepted
3,503 posts since Jan 2012
Reputation Points: 824
Solved Threads: 481
Skill Endorsements: 58
You can actually reply to PMs that were sent to you, initially. You just can't send out PMs unsolicited.
Dani
The Queen of DaniWeb
21,582 posts since Feb 2002
Reputation Points: 1,555
Solved Threads: 377
Skill Endorsements: 124
Why do you need to PM anyone? Getting help is done by posting in the forums.
Read the Member Rules.
WaltP
Posting Sage w/ dash of thyme
11,404 posts since May 2006
Reputation Points: 3,421
Solved Threads: 1,055
Skill Endorsements: 37