There is already an option called "Use SSL Version 2/3 Mode With TLS" in each listening service. If you leave this unticked which is the default then there is no vulnerability as TLS connections won't try SSL 2 or 3.
That's because WebMail can only use implicit SSL so SSL negotiations are done on connect rather than after the connection as with explicit SSL. Only explicit SSL connections have the "Try SSL if TLS fails" option so WebMail is not affected by this vulnerability at all.
I'll investigate this further and if needed add a new setting for all implicit SSL to only use TLS and not any versions of SSL. It used to be SSL 2 that was unsecure and SSL 3 was ok but a lot of years have passed and now it seems that possibly only TLS is deemed secure so an option to disable SSL 3 is probably needed if possible.