Still have nightmares from my first job in help desk, sweating bullets while handling decades of Outlook .pst files for a C-level in my company. Only place they existed were on the laptop itself, and a cheap 250GB external drive.
Email sucks.
Email sucks.
The cheap VM running sendmail with 12,000 entries in its alias file was being DOSed....
That was my introduction to crappy large email systems!
Looking back, I should have suggested backing it up to network storage. I imagine it must have been stressful traveling or going through TSA and worrying about losing 20 years of email data.