After further investigation, the messages are coming in via our email system - Nothing at all to do with Henri (steamyacht).
It appears that one of the spammers/hackers may have found a security loophole in the email software - I've reported it to the authors, but if the problem gets worse I will have no choice other than to delete the software.
I apologise to everyone that takes the messages on Paddleducks via email, as that means you will have to log on to the forum to read and reply to messages, but if this gets worse (as I expect) I have no other choice...
If that situation arises I'll email those concerned...