Knowledge ties. We assume that if A sends a message to B that A 'knows' B. (We do not assume that B knows A).

Awareness ties. We assume that if B receives a message from A that B is 'aware' of A. Likewise, if B and C both receive a message from A, we assume that B and C are 'aware' of each other.

Trusted ties. If A sends a message to B and blind carbon copies (BCC's) D, we assume that A 'knows' and 'trusts' D. We assume this because D has the ability to respond and reveal that A included people without B's awareness.

Additionally, we assume that most senders do not distinguish between the To and CC fields so we treat them identically (referred to as the To field from this point forward). We also assume that if no one is in the To field and everyone is BCC'ed that privacy is assumed and that there are no trusted ties. As we only have the messages that Mike received, we only know the people that he BCCs and the people that BCC him.

Example. Imagine the following messages:

From: Mike
To: Drew, Taylor
BCC: Morgan, Kerry

This produces a set of ties as follows:

Mike knows Drew; Mike knows Taylor

Mike knows & trusts Morgan; Mike knows & trusts Kerry

Drew is aware of Mike; Drew is aware of Taylor

Taylor is aware of Mike; Taylor is aware of Drew

Morgan is aware of Mike; Morgan is aware of Drew; Morgan is aware of Taylor

Kerry is aware of Mike; Kerry is aware of Drew; Kerry is aware of Taylor

We maintain bi-directional links in order to understand the strength of ties. Using this information, we construct a matrix of ties.