Page hangs when approving moderated users
 

I have it set so every user that registers is moderated. I look over their details, make sure they're not a bot, and approve them. I've been doing it this way for years, no biggie.

Fast forward to last night. I moved the site to a new server. That's been an adventure, but anyways. Now when I go to approve a new user, the page hangs ONLY if the radio to send them an email is selected. If I chose not to send them an email, it goes through just fine. If I just let it go, it comes up as a blank white page. I've already read the FAQs on here about white pages. Nothing fit this. I disabled all plugins, and still the problem persists. The real kicker is, as soon as I hit submit the user is approved an the email is fired off. The page just never gets a response back or something. What. The. F*ck.