Update 08.03: Looks like this is the issue: Email service providers can't send to / from Yahoo addresses, which took effect on April 15 of this year. Since I had the email "from" address in Feedburner configured to archidose[at]yahoo[dot]com, many people (including myself) were not receiving this blog's subscription emails for the last few months. I just switched the "from" address to my gmail account, so let's hope that does the trick.
It appears that the email feed for this blog has not been performing properly lately, so I'm trying to get it working again. If you notice anything odd with your email subscription/rss feed it is due to me working to correct things. Hopefully the email feed will be working again soon.