If you upgraded your site to 2.5.3 v.s. a fresh install, the following guide may interest you. Even if you did a fresh install you can still use the guide (it may help you understand the noficiation feature), but it is mostly meant for those who upgraded.

When a member logs in to his account, he or she can change certain setting to their account.

By default, "Limit notifications to one per day" is set to yes. What this does is limit members  to receiving  one notification per day even if they have several notifications on that day. The positive of setting it  to yes is that it helps with  possible spamming issues. The negative if set to no is that a member who has, for example 5 notifications on a certain day,  will only receive one notification that day. As the webmaster of your site,  you have to decide which setting is best for your site goals.

If you want to change the default setting in the CP you do so at Settings - Under the drop down choose Registration - Click Defaults:

The problem is after you make the change in the CP it is NOT retroactive. Meaning,  even though you made the change in the CP for the default setting to be no, any members that was added to the site when you upgraded to 2.5.3 will have their setting set to yes since they were added to your site prior to you making the change in the CP. In other words, all members who sign up for your site after you change it to no in the control panel (CP), their account will reflect the default setting of no for "Limit notifications to one per day" but not for those who signed up prior to the change in the CP.

I  don't want to debate the issue of which setting is best. You decide for your site --  if you prefer it to be yes, than leave it at yes. I just want to provide a guide to those who want to change the setting to No database wide

Thanks to Vlad for providing the sql query code for the database. Highly recommend you backup your database before making any changes. How you backup your database may vary depending on your host. I prefer to use phpmyadmin and I'm sure a vast majority of vldPersonal users have the same setup but I can't guarantee it.

Here is the sql query I want to use to make the changes in the database so all member's account reflect No for "Limit notifications to one per day" in their setting.

update vld_members_conf set notify_limit=0

Now it is time to go to my site to see if the query did its job.

YOU DID BACK UP BEFORE DOING THE SQL QUERY IN CASE YOUR RESULTS WERE NOT AS SUCCESSFUL AS MINE WAS -- IF YOU DID AND GOT AN ERROR, YOU MAY NEED TO RESTORE YOUR DATABASE.

If you want to check the setting in the CP go to Manage Members - click a member's username - than click the Notification link at the top of their setting.

That's it. I have another 2.3.1 site I will be upgrading to 2.5.3 in the near future and I will once again use the above query to change the setting  to No database wide.

Thanks vlad for your great support!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!