Netmail where the "authentication" section of your mail route is configured to query eDirectory via LDAP.
Not everyone wants their groups or resources to be mailable from the outside world, for that reason, by default the Groupwise LDAP authentication route in Netmail will only find object which have an object class of "person" or "inetOrgPerson" such as user objects.
If you want to accept mail from the outside world addressed to your groups or resources we simply need to edit the authentication route to include the object class(es) for those type of objects.
1. Go to WebAdmin > Domains & Users > <domain> > Details tab > LDAP Search Options > Class Name.
2. Add the word "group" for groups and "resource" for Resources. Separate each word with a comma. (inetOrgPerson,nGWObjectID,Person,user,groupwiseDistributionList,nGWAccountID,nGWExternalNetID,nGWFileID,nGWGroupWiseID)
3. Restart the mplus service with:
service netmail restart