I first read that as faxyourrump.com

Then again, depending on your MP, that may be what you want to do.

What an excellent letter! My favorite bit:

Were we a bit less civically-minded, we might send you a copy of every refused mail with a note attached saying "Remember not to do this again!".

However, we won't. This is because we are lovely.

You, however, have been very bad, and this is your punishment:

Please carefully read this email and then ask one of your volunteers (preferably the one who wrote your original mail) to write an explanation, in words that would be best understood by organisations like the [Big Charity], about why what you did was such a bad idea, and how they can avoid doing this in future.

Then mail it to us, and we'll put it in a prominent place on our site, so we can encourage other large charities to read it before they do what you just did. ...

According to the latest NTK newsletter, the charity in question is the RPSCA.