Verizon Online’s anti-spam system is currently blocking all email from the forum. I asked for it to be whitelisted, but that was bounced because Verizon say the site does not have a reverse DNS entry, which it does. Digital Ocean have confirmed there is no issue with the DNS, and that they are trying to get Verizon Online to resolve the matter. But if you are a Verizon Online user, please note that you will currently not get any email messages from the forum you might be expecting, and you may want to complain to them that they need to figure out their broken anti-spam system.
Sorry for any hassles - normally I just ignore broken ISPs, but this would seem to be affecting a fair number of folks.