I don't use Gmail for personal, but a former small employer used it for business, and thus so did I for that business (only). But I used Thunderbird for access

I don't use Gmail for personal, but a former small employer used it for business, and thus so did I for that business (only). But I used Thunderbird for access, which was set up to make local copies. When I was -- ahem -- fired, they soon said that I had something that was theirs. But I had given that something to another employee, who was now saying she had given it to me. Although I no longer had access to the company Gmail account, I had my copy of the email thread where the other employee and I discussed the handoff of said thing from me to her. And that was that. If you use any Google or other company's service for something important, it's good/essential to make backups.