How to block a redirected (and obsolete) email address.

[#1]

Years ago, I got an email address from an organisation. I had all mail to that address redirected to my plusnet account. This was done by the organisation

That organisation is now defunct, but I am still getting redirected mail from it (mostly, if not completely, spam)

How can I block redirected mail? I appreciate that spammers change their email addy all the time, but this address is fixed. i.e. from: spammers at spammers dot com to: me at defunctorg dot org (redirected to my plusnet address)

Any help appreciated. 

Moderator's note by Mike (Mav): 2 posts released from Spam Filter and duplicate removed.

[#2]

If the organisation who provided an email address has gone out of business then that should’ve stopped working along with the redirect with it? Has the organisation changed hands to someone else?

[#3]

Unless you used an alias for that mail (then you could blacklist it in your mail setup) it does not look possible with the Plusnet options.

Your e-mail client may be able to filter and delete messages that are redirected from "defunctorg dot org" by matching that in the header - possibly a "received from" element. I don't have any redirected e-mails to check.