User can report to admin someone who is sending unsolicited PMs and that will result to a ban.
Just like the case of
Hhampuz , you can find his explanation in his thread entitled Hhampuz Ban Appeal.
Though his intention was good and explained been doing it for many times already, but one report maybe resulted it to a temp ban.
Personally, I have received a lot of unsolicited PMs in the past during the times when ICO was still hot but just ignored it, I just think it's normal in this community where a lot of active people.
But in the end, it's still based on the discretion of the receiver, he can report it and let the admin evaluate the report.
He also seems to be breaking a forum rule:
Forum rules
29. Sending unsolicited PMs, including but not limited to advertising and flood, is not allowed.