Wow, that is a little hard 🙂 I will try reducing the size, but I need at least 2013 + 2012 emails operational, which is most of that 30 GB... here are some good email management tricks from me:
http://www.janrezab.com/good-tips-how-to-tackle-email-and-some-useful-email-mana gement-tricks/
But the problem is many of these tricks dont work properly without mac mail, Outlook just doesn't provide the speed Mac mail did.
The archiving / moving is also an essential functionality for me, which is the only one that seems to be working at this stage (I have a shortcut for moving to a dedicated archive folder, the folder must show in IMAP, or Mac Mail doesnt know how to move it there, and going back and forth seems senseless.
Apple made a great way how to downgrade email...