Anyway, I tried sending out a PM so the user could understand what is at play and perhaps bring his or her attention to this thread but, forum default system doesn't allow PM between newbies and ranked members.
There is no such option in the profile settings. You can only allow or disallow newbies to send you PMs, but that doesn't affect your permissions to PM them. If your settings don't allow newbies to PM you, you can still PM them. Each user can customize their own ignore list though, which allows you to add any user whose PMs you don't want to receive. I don't know why that user would add you to his ignore list if you never interacted with each other before.