I don't know why they stopped sending us the letters, but I'm very happy that blogger has resumed the service.
To get notifications of comments the blogger must check the relevant section of the "set up" page. And if you used to get the notifications and now don't, you should have gotten a letter from blogger asking you to click that you want them resumed. If you haven't received the letter, it may be in spam. Check there, and/or do a search in your mail program for comments.
Happy blogging.
