I think that you may want to use a join table. If both your 'OWNER', and 'NODE' entities have a primary key (unique number), then creating a join table that has a foreign key for each table would create a unique join table. A NODE could be associated with any number of OWNERS and an OWNER can have any number of NODES

+--------------+              +-------------+
| OWNER        |              | NODE        |
+---+----------+ <---+  +---> +---+---------+
|PK | OWNER_id |     |  |     |PK | NODE_id |
|   | other    |     |  |     |   | other   |
+---+----------+     |  |     +---+---------+
                     |  |
               +--------------+
               | MAILING_LIST |
               +---+----------+
               |FK | OWNER_id |
               |FK | NODE_id  |
               +---+----------+
[download]

Join tables work great for associating data from one table with data from another.
Updated: Oops. misnamed an element.
Updated: Forgot to name the join table:\

HTH - Kristofer