The lists that NetCommunity did not send to may have been based on static queries and they may have not been properly loaded/refreshed in NetCommunity prior to sending the message. For lists based on Dynamic queries, NetCommunity will refresh the list automatically prior to sending an email to such a list. However, NetCommunity does not automatically refresh lists based on Static queries.

A best practice when sending to lists based on Static queries is to save the query in the source application (such as Raiser's Edge or Education Edge) and refresh the list in NetCommunity just before sending the message. By doing so, you are able to see that the list loaded successfully into NetCommunity prior to the message being sent.