I try and open an e-mail and all I get back is 'e-mail has stopped, close app' - now it is doing it with other appzas well.... e.g. Just Eat.
Nothing has changed, it just started last night. (18/10/2018) - all my desktop and web e-mails work fine.
If this was happening on my phone @kriptikchicken I'd first try a soft reboot by turning the phone Off and On.
If that didn't resolve the issue then I'd go into Settings_Apps_my email app_Storage_ and clear the cache and data.
If no resolution then I'd try another email app and or delete my email account out of the phone and reset it back up.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.