We've had reports of bots PM spamming people. We don't want our users to be tricked or spammed when using this site!
What we've done to tackle this is that now only users with 200 or more reputation can send PM's.
If you have less than 200 rep, you can still receive PM's but you just can't send them. I hope this small change will make Scirra a lot safer for our users!
Please do report any spam PM's to us if you receive them, the best way to reach us is probably by email.