Every time I get out my 2013 MBP (not for the day job) I remember what a computer could be.
Docker - I don’t use it, but if it’s anything like the VMs I use to run, it also kill batteries.
I’m better off provisioning all of that on our DEV AWS Account and just connecting via my phone’s hotspot if I don’t have a reliable network connection and running very few things locally.
I used to use Outlook Web and might go back. The native client is a nightmare but does some useful things the web one doesn’t.
Docker has been a huge boon to my dev efforts, usually much lighter weight than an old school VM, so I’m no hater but if I had to work on battery more often I’d probably do the same thing, spend a few bucks on AWS and only work online but with better battery life.
All that still won’t get me more than 6h though.... :-(
Is Mail.app, or some other mail client, an option for you?