Abstract: Methods and systems to find connections among subscribers to a particular electronic mail (email) newsletter. A list of email addresses to an email campaign is representative of the subscribers to email newsletters that are sent as part of the campaign by a source. A subscriber to a particular email newsletter may receive email newsletter from other sources. A determination is made as to what other email newsletters of each subscribers of the source receive from other sources. The other email newsletters of each subscriber on the list of email addresses of a source are compared to the other subscribers on the list of email addresses. Email newsletters common to subscribers on the list of email addresses are noted. The connections between/among subscribers on the list of email addresses is determined. The weight of a connection may be determined. The connection information may be provided as a service to the source.