Sometimes, given the content of the emails from your members ( eg. a flyer for a Tupperware sale for instance ) - Gmail, Yahoo etc. will flag the message as spam, and will not get to your inbox.
Here are the steps to whitelist ADDA emails:
1. In Gmail Inbox search for firstname.lastname@example.org at the top toolbar
2. Click on the More Button and click Create Filter
3. Click Create Filter with this search
4. In the resulting screen select Never Send it to Spam and click Create Filter.
Now ADDA emails will not got to Spam and will reach your inbox all the time.