The number one rule when storing data in the cloud is that the data must be encrypted, particularly when it's confidential emails of politicians. Sorry to say, but Gmail is not an option either. https://news.sky.com/story/parliaments-email-system-less-secure-than-gmail-says-mp-hit-by-chinese-psy-op-emails-12274853
Better check out Tutanota: https://tutanota.com/
The number one rule for official government correspondence is that it must be secure but able to be audited so that politicians can be held to account. This is particularly important when you consider the bunch of crooked chancers who are running the UK at the moment.
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