Best practices for email security?

[humptydumpty]

I just read that some vulnerability exposed “millions” of Gmail users. I just read the title so please don’t ask for details. But, it got me thinking about our CR mail servers. How can we best protect them?

From the user side, I was thinking that if we use thunderbird to archive emails and delete them from the server then that would lessen the risk in case of a breach.

@girish you have this setup so your two cents are much appreciated.