Not really a convincing reply, more like an advert for a couple of paid (= £££) services. Of course, VM have access to logs so may have additional information but from the OP question, this could also be a bad guy spoofing the OP email address or even other naughty happenings.
I don't usually frequent VM forums because of this kind of reply and I haven't used the mail servers since... er, well, CableInet or possibly BlueYonder. I nipped over to see how VM were implementing DKIM and DMARC but I suspect I'm wasting my time. And what is this latest VM mail snafu :-)
IMHO, normal folk should use GoogleMail/GMail, the seriously keen should use a specialist email provider and the lunatic geek should use a Raspberry Pi running Postfix et al.
Thank you for your comments. This was not spoofing, the emails were sent after an authenticated SMTP login. The advice we offer to customers is designed to help them and decrease the chances of our platform being exploited in the future.