Related to this: I had a hard time remembering my password after receiving the notification (I finally did), but I tried the "reset password" functionality and have yet to receive an email. Since I received the expiry notification emails, I suspect it's not a general sending issue and not related to my email provider.

Edit: I should add that I did receive an email now, after having logged in, changed my password, and logged out and in again. So the issue, if it still persists, may be restricted to inactive accounts or amounts with a very old password. Either way, people with inactive accounts having forgot their password may have a hard time activating their accounts again.