Email issues - VM email accounts not receiving opted in mails
Our association has an 'opt-in' mailing list that is used to send around 2 or 3 messages per week to our 1,500 or so members: I operate my own exim-based SMTP mail transport agent and therefore provide the means to send out these messages.
About 100 or so members have Virgin Media e-mail addresses or legacy addresses that are handled by Virgin Media's MX servers and I've just spotted in relation to a message sent out about 16 hours ago that none of Virgin's mail servers are accepting delivery attempts... exim reports "Connection timed out: SMTP timeout after RCPT TO:<(customer's e-mail address)>.
All of the other 1,400 messages to non-Virgin customers were delivered at the first attempt and I use Talos Intelligence to make sure that the reputations of my domains and IP addresses are monitored for blacklisting. Are all of Virgin's mail servers down?
[MOD EDIT: Subject title changed for clarity]