Export email threads and emails from specific addresses.

Hi Guys,

I have a pending litigation lawsuit and need to export all my email threads of communication with the defendants .. Is there a way to do this via each thread which in Apple mail becomes very hard to follow, or is there a way to export all communications from certain email addresses?

I have the same question regarding text messages and group text messages on the iPhone.

Any help achieving this is greatly appreciated.

Thank you.