Yes, though you might not like some of them. If you did not already try removing the affected Accounts and adding them again, that's a necessary and probably unpleasant step. Unpleasant because like many other formerly "free" email services Earthlink (and even some paid ones) got out of the email business because there's no money in it. Some other company (probably Google) now handles all @mindspring.com traffic, which of course means they're reading your emails to harvest personal information they can sell.
No matter though, I understand your desire to keep perfectly good @mindspring addresses and that's where I would like to help. Unfortunately Earthlink's most updated instructions for Mail are woefully outdated:
https://help.earthlink.net/portal/en/kb/articles/mail-for-mac-os-x-10-8-5
That Mail version must be a decade old. Those instructions are not likely to work at all. Adding that Account to Mail again is likely to require their support, which I started with here:
https://help.earthlink.net/portal/en/kb/articles/how-to-add-a-new-email-to-your-account
That's what led to the unhelpful setup instructions above. Perhaps their chat or phone support has more updated instructions.
Here are my thoughts, since you asked. Email is supposed to be easy. If an email service too becomes difficult to use, or if the "free" service they provided in the past turns evil, abandon it.