The useful starting point
Synchronisation keeps working copies aligned, an export records information in a chosen form, and a recovery copy supports restoration. These functions can overlap without being equivalent. A convenient email export may omit some context or require a compatible reader.
A small step to try
Record what the chosen export includes, how attachments are represented and whether you can read the result. Keep important recovery copies appropriately protected and test a representative restore through an approved process. Library of Congress format material explains preservation considerations; it does not guarantee that every provider’s export contains the same fields or meets your recovery needs.