It’s not a big deal to me and I’d rather have control over the services and, more importantly, the data. And my rented server is cheap.

It seems you want a list of email addresses, at least, but don’t have the emails themselves, correct? If so, do you have access to the mail server? If so, what operating system, what mail service, do you have access to the logs?

For example, I run my own mail server. If I lost my emails, using the logs, I could extract the sender’s address and the address (actual or alias) the sender sent to.

I have several VPSes around the world each with OpenVPN.

Too little info to give much of a response, but I’d grep the mail server log.