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.
I still remember the conversation with a senior IT support guy who had been sent my way by the CIO - "<boss> says to speak to you as email is broken". "How much of it is broken?", "All of it"....
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!
I asked them that directly (it was a tiny company and I was like 20) and the answer was no, but that they wanted to hold onto them in the event they needed to look up old contract info.
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.
Email sucks.