For legal purposes, it is recommended (where possible) to retain e-mails in their native format (e.g. MSG for Outlook e-mails, EML for Google-mail, Thunderbird etc.) along with all associated metadata to preserve provenance, authenticity, integrity, and evidential value.
For regulatory inspection purposes, it is acceptable to retain e-mails in non-native format (e.g. in paper format or PDF format) although caution should be exercised to maintain the integrity of the e-mail as much as possible.
Author: Dr Leire Zúñiga, Director and Principal GCP Consultant
PHARMITY, 26th of October 2020