OP: From addresses are not to be rotated. Each communications channel should be in a compartment. Compartmentation requires minimizing the amount of information leaked, not maximizing it by contaminating a large number of addresses.
For more information on compartmenting and unlinking relationships, see [1].
This guide is not a complete COMSEC plan. A complete plan would be tailored to match the circumstances and requirements of the actors involved. This is a collection of notes and best practices. They need to be adapted and actively applied for the situation.
A complete COMSEC plan would include things like setting up dedicated email accounts for correspondence, creating the corresponding PGP keys. The confederates would exchange contact information, either out of band, or via another exist secure channel. Information exchanges would be via PGP email with fixed subject lines and only relevant information inside the content. All emails would be deleted in a rolling 7 day window.
[1] http://grugq.github.io/blog/2013/03/18/the-paddy-factor/