Undeletable e-mail in Mail - the latest! How can I get rid of it?

Question

Following my recent posts about an undeletable e-mail received as undeliverable mail (I never sent it in the first place so it's obviously coming from a virused address book) I now have 13 copies of an identical e-mail which won't go away. My Mac says they're junk, but they're in the inbox and when I move them manually, they leave the inbox but don't appear in the junk. Once I return to the inbox, there they are again - with one more copy. There is no visible body, just a header stating:
"Subject: A hacker can access a public web site linked to an internal distributed file system and gain access to company and customer files."
I recently went to a PC forum for help and when I copied and pasted the header onto their forum , a green link appeared under the words "web site" taking me to a site "zimki.com" with whom I have never dealt.
How can I get rid of these self-generating e-mails?
Incidentally this message is not on my server as web mail access was used to delete it, so it only appears on the Mac.

Answer 1

Yes I did repost, as the original problem - a huge e-mail downloading - proved not to be the case so this is a more accurate description of the problem in the hope that I can get a more accurate solution.
I used the edit/ cut solution (thank you!) which removed the e-mails from my inbox, but they're now back with a vengeance including about twenty copies of one entitled "fez" (a virus maybe?) - I now have two of every e-mail downloading; my Mac tells me this fez message is junk but now adds that "You need to take this account on-line to download this message" - except the download in progress wheel keeps going on, and on, and on....and the new messages in my inbox (I now have two or three variations on the original theme) won't go anywhere except by edit / cut.
I'm tearing my hair out!!!
I've just erased all the messages by webmail, 52 messages, so it appears my Mac is also no longer automatically erasing the messages on the server after download even though the box for this is ticked.