Corrupted Maildir. How can I push Thunderbird emails back to the server?

I’m transitioning from a VPS to DigitalOcean after my machine suffered a catastrophic failure due to a loss of power, resulting in a completely corrupted Maildir folder. Now, I’ve got two accounts in Thunderbird:

• Account 1, with everything still stored on my local machine.
• Account 2, with new email coming in.

Now, when I connect back to the corrupted host, because it’s running on IMAP, it dumps all of the local data in Thunderbird (good thing for local backups.)

When I move to DigitalOcean this week (I’m installing software to the droplet now!) I’d like to setup a new mailserver and a smooth transition, and as I’m doing it, it would be really nice if I could combine these accounts and retain the folders, and consistent email history that I’ve lost.

I’ll be using this guide:

https://www.digitalocean.com/community/tutorials/how-to-setup-exim-spamassassin-clamd-and-dovecot-on-an-arch-linux-vps

Does anyone have any suggestions?

Thank you.