Hi Janette
As Disco says, when you make a post, one of the check boxes at the bottom of the screen says 'Receive email notification of new replies?' On our forum the default is for that always to be ticked, and if you keep it this way you should always receive email alerts.
The 'tick' against this box is what is known as a 'subscription' and if you go into your your 'User Control Panel' and into 'Subscriptions' you should be able to see all threads to which you have 'subscribed' - ie said you want to recieve email notifications for.
A little while ago I posted a thread in 'Announcements' asking if everyone could get into the habit of clearing out their subscriptions (something you can do within user control panel) as they take up a reasonable amount of database space. If you went into there and deleted any of them, that will be why you are no longer receiving email alerts.
As a general rule it would help us if you could all go into subscriptons every so often and tidy it up. That doesn't mean you have to delete everything, I go into mine about once a week, and any of the older topics that people are not really using I delete the subscription for, but leave the newer ones and any olders ones I have a particular interest in.
I hope this helps, Janette. If you get any further problems let either Mark or myself know and we'll see if we can help.
