The OR operator is always implied as the connector between senders and recipients list within
a rule.
The AND operator is implied within a given list. In other words, all items on the same line,
delimited with a comma, are connected. For example, the entry:
1@domain.com, 2@domain.com, 3@domain.com
means 1@domain.com AND 2@domain.com AND 3@domain.com.