29. Sending unsolicited PMs, including but not limited to advertising and flood, is not allowed.
I have a question about this rule that I don't know if it has been asked and answered already in any of the 48 pages of the thread.
What does "unsolicited" really mean here? I mean, if I send a PM to someone on my own initiative it is always going to be unsolicited. I imagine it's a way of saying that any PM can be reported and the moderators will exercise their judgement on the provenance of that message, or not. Is that so?
The answer is "it depends". If a user has not indicated that he's open to certain (or all) commercial communication, sending such PMs would be considered as unsolicited. When it comes to non-commercial or ambigous types of communication, if it's not something the user expects nor something a regular user (as per the moderator's discretion) would expect, that would count as unsolicited. So while thanking a user due to the helpfullness of their post via PM would be unsolicited, as with all rules, a moderator's discretion applies (see rule 23).