I seem to have stopped receiving email notifications for my subscriptions. The last new chapter notification email I got was on March 3, and there have been many chapters added to my "To read" list.
I'm getting notification emails again (new ones, not any from the previous days).
Just a FYI, am pretty sure you only get email notifications on the items in your Subscribed list
There's an option to "Add notified chapters to To Read list". If, per @MZH, the site is adding the chapters to "To Read," then the site at least thinks it's sending the notifications.