To the responsible IT guy of BitcoinTalk.org Forum:
Since the September 2016 (
probably related to this attack) the mail deliverability is limited to few mail providers. Some mails
such as notification or password reset won't arrive to the mail server because of the misconfiguration in the DNS configuration.
This problem shall not occur at big forums such this one, and shall be fixed as soon as possible.
Thank you!
How are you under the impression there are only some mail providers that are working? And which are they?
DNS doesn't have a huge amount to do with mail delivery except to get SPF or MX records to determine where mail should be delivered, or where mail should be coming from, in relation to a specific domain. I'm not sure if the outgoing emails of the forum go through a proxy before sending out but assuming the destination domain has accurate MX/SPF records, I would guess the messages are making it to their destination server.
I'm not seeing the BTCTalk mail servers listed on any RBLs so I would only guess that destination mail servers are blocking the messages for some reason and would need more information on which providers to try and explain why.