PLEASE - set the default on receiving PM's to "allow" and let us decided if we want to not allow this. It seems like if you want to set it for "not allow" than it should be clearly explained and in a bright, bold way that not changing this setting will keep other members from being able to send your forum account any personal message and this is not to be confused with spamming your personal email account although you can set up personal email notifications as well/or not.
A newer member made a comment about some gear that he was using that I wanted to ask him about. I quoted him and asked him my question and then tried to PM him to let him know about my question in the thread but likely because it is defaulted for him to not receive PM's, the only way I'm going to get a reply form him is on the remote chance that he happens to find my post sometime in the middle of the thread.... pretty unlikely.
This is a "forum" - I don't think anyone would be surprised and object to receiving a PM if they could then decide to not allow PM's.