Help! All email notificaitons broken

I recently had all email notifications stop working for my blog. No email of any sort works: update notifications, comment notifications, recover lost passwords, spam karma reports, etc. It all doens’t work. I didn’t change anything on the site to cause this, and nothing on the hosts end has changed.

I am using the latest WP 1.5.2 and these plugins are what i have installed:
SK2 2.0 final r4
AMM 1.5
Bad Behavior 1.2.3
BDP referral tracker 1.0 prerelease b
bunny technorati tags
subscribe to comments 2.0
wp email notification 2.3.0

I’m going crazy with my limited know-how trying to figure out what happened. My host tells me he changed nothing at all on my domain so I doubt the fault lies there. I have a ton of subscribers, plus rely on my comment notification as I get lots of comments and now I feel crippled without it working.

Can anyone help at all? If it helps, the site in question is https://www.punkvinyl.com

thanks in advance.