I’m unsure about how we will provide users with a copy of their personal data. Is there any guidance on this? What type of data should be send to them? Eg. can ex-employees request copies of all emails they sent ?
You need to provide the data subject a copy of the information you have about him basically copies of the documents where their personal data is mentioned.
Regarding ex-employees this needs to be assessed because the emails might me subject to copyright or contain copyright protected information as well as personal data of other individuals and in this case these date need to be removed.