Eudora is not longer being supported and it is now end of life. The problems; will continue even if we fix this one and the reason is simple. Since it is not supported, no updates and nothing; it is difficult for Eudora now to cope with the changes the industry is making. Such as the SSL Issue, which is required by servers for encryption. If you ask for my advise, then i would suggest that you switch to Thunderbird; it is easy to do and you will be able to import everything from Eudora to Thunderbird.
if you have decided to switch, then follow steps at add your account to Thunderbird.
Now, if you would like to fix the issue with Eudora, then follow these steps:
1. Locate the personality you are having issues with. Once you have identified the personality you’re having issues with, open it in the personalities window.
2. Right click the personality and select “Properties”
3. Go to the “incoming mail” tab and click on Last SSL Info.
4. Choose Certificate Information Manager from here, you will see list of certificates.
5. On the top under the title server certificates, there will be a number of certificates for the problem server (pop/imap). Look at the + next to the certificates, and click
6. Continue to click on the + sign until all of them are open. Now, look carefully for the smiley faces and the ones with the skulls, those with smiley faces are the ones Eudora trusts, and the one’s with the skulls are the ones it doesn’t trust, which is why we get the rejected error.
7. Now, choose each of it, and select add to trusted, and then exit out of it by clicking on the appropriate buttons.
8. Test and see if you can now receive and send mail.