I am not too concerned with the security aspect of putting my mail on the SD card, I am however very interested in moving the mail storage from the phone's internal memory to the SD card.
I have looked at the Gmail app and the stock Mail app and neither of them seem to be movable to the SD card so does anybody know if this can be done?
To be more specific, I really do not need to move the app itself, only the mail storage so if there is a way to move the storage location of mails from the internal memory to the SD card I would be very interested to know how that is done.
K-9 Mail supports to store mail on the SDCard. So if you're not bound to the GMail or the other pre-installed mail apps, this might be worth a try.
Details can be found e.g. at TechnosAmigos article How to Save Email Data on your SD Card Rather than Internal Memory on Android Phones/Tablets. Basically, it requires the following steps:
Only if you rooted, you can use data2sd (original version at Google Play; later modification by enthusiasts at XDA), where /data/data linked to /sd-ext/data (or just sdcard mounted to /data). Then ALL application data will be stored on SD Card.
K-9 Mail's option Account Settings > Storage will allow you to save messages to the first SD card. Most smartphones have no internal SD card, only the external. Thus my (Android 4.1.2) smartphone stores to
/sdcard/Android/data/com.fsck.k9/. Most tablets have an internal and an external SD card and K-9 uses the internal. My tablet (also 4.1.2) stores to
/storage/sdcard0/Android/data/com.fsck.k9/. AFAIK K-9 cannot store to the removable SD card sdcard1.
The ability of storing your email on autonomous madia by default, such as an SD card has become imperative in the age of claimed hadking. After all, it's the only way to efficiently preserve your email, possibly essential for later legal purposes and if we do not want to remain at the mercy of certain tech giants. With this being said, the ability to save your emails directly onto SD card within the k-9 email app as described above HAS DISAPPEARED in the second week of June 2019, which to my knowledge was the last email app offering this feature (The real reason it's disappearing everywhere!)