I can see why you are trying this method to weed out the spammers (based on the discussion about this that you were having on another page). Hopefully it might work, at least until you get a more durable solution.
The only downside that I can see, besides the extra work involved both for the Admin & the applicant, is that people might be reluctant to post their email address in the open, in a public forum. Personally, I wouldn't do it myself - because either human spammers or web-crawling bots would eventually find it. Also, they might receive a fraudulent email from someone pretending to be from this website.
A possible measure to counter-act this problem might be to advise people to set up their own temporary webmail address specifically for this purpose. You could give suggestions (eg. Gmail or something like Mytrashmail).
Alternatively, admin could set up its own email account especially for DIY Wiki account requests. You may need to create a filter for the inevitable spam you would get. This could remove all email you receive except that which is in the correct format of Real Name, Username, Email Address, or which doesn't include a specific keyword you tell the applicant to put in their subject line.
Thanks for the input. The situation as it is now is obviously not ideal - but the level of fake registered users and their spam was becoming a pain. I suspect a little more explanation may help mitigate some of the problems you raise. For example putting the email in a non machine usable form. It is also worth noting that the changes to the account requests article gets flagged to me - so the actual account request will not be up for more than a few hours before the account gets created and the request deleted. Regular users of the newsgroup are also able to post requests there or directly to me, John S / YAPH or NT anyway. I will probably also setup a request address and document that.
 experiences suggest that obfuscated addresses rarely attract spam - 99% of it is automated harvesting that does not bother to render the HTML and just searches the plain text for "mailto:" format links.
--John Rumm 16:16, 18 June 2009 (BST)
Account for Barrie King
I have created an account for this user, however the email specified does not work. So if you read this in the next few days Barry, then drop me a line so I can send you a password.
If I have not heard anything in a week or so, then I will remove the account.
--John Rumm 22:35, 14 April 2010 (BST)