It's simple to tell which members are using the Spond app:
A Spond symbol will appear on the profile picture or the initials of those that have downloaded the app. This can be viewed in the member list in the app or on the web:
If the symbol is an envelope, the member is receiving notifications by email. Read more here.
If there is no symbol, either this member has no contact info registered in the group or they are a child member.
If there is a yellow explanation mark, you can click on the member to see what the error is. Often it means that the member has not yet accepted the group invite. Whenever an event invite or post is sent to this person, the person will receive a reminder about the group invitation.
If you would like to remind members about the app, go to the group, press the 3 dots within the menu and 'Get even better responses'. You will then be able to write a short message about why they should download the app and they will receive this either by email or SMS.