I've updated the server so that it now emails Diarists to let them know when they have new followers. This will send at most 1 e-mail per day, at 20:00 GMT. This is done to prevent malicious users from just keep clicking your notify icon and spamming you with e-mails.
If you don't have any new followers to your diary you of course won't be e-mailed.
However, the system is not (and cannot be) retrospective. So you may have users who are wanting to be followers to your diary (or diaries) but you've not authorised them to receive notifications or read your followers only entries because you didn't realise they were there.
Have a look at your diary settings (Click the Dashboard icon, then the cog icon beside each of your diaries) under the Followers tab and make sure all those people that you want to follow your diary have a little green 'eye' icon next to them. If they have a red icon with a line through it that means they're not authorised to read your followers only entries and won't be notified when you make updates.
If you have any questions, suggestions or dramas please drop me a comment or use the email icon at the bottom of the screen 😀