No specific info about version 11.5. Please visit the main page of Mail on Mac Informer.
While it certainly have some advantages, I believe Mozilla Thunderbird is the more useful mail app.
Serial Mail is a plug in for Apple Mail to generate serial mailings.
Mail Scripts is a collection of AppleScript Studio applications for Mail
It can forward mail from AOL, Gmail, Hotmail, MSN, etc. to any e-mail address.
Organizer and archiver for Apple's Mail.
Use Mail-Grab to extract email addresses from your Mail app or text files.
While it certainly have some advantages, I believe Mozilla Thunderbird is the more useful mail app.