I expect that Evolution is not using the same IMAP requests as
Thunderbird did. Thunderbird was getting the server to parse the email
somewhat and give it the details. Evolution may just be asking the
server to send it the whole thing. I don't know if Evolution has some
way to log the protocol like Thunderbird, but it's not necessary.
Install "socat" and run the following command as root in a terminal:
socat -v tcp-l:143 openssl:your.mail.server:993
Then create an account in Evolution that connects to imap (not imaps) at
"localhost". When it connects, you will get a full log of the protocol.
You might want to log to a file instead. You can do that by adding
"2> my.log.file" to the end of the socat command which redirects the
stderr output to the file.