Best Email Client (Mac) for old Eudora ADDICT!!

[Kass Johns]

Hi gang!

It's been forever since I visited the Forum, but I need some advice. I cannot seem to get a clear answer in my research over the last year (and longer). I have a brand new MacBook (w El Capitan) I will not use yet for fear of letting loose of my Eudora on my old MacBook w/Snow Leopard. I know many of you "old timers" like myself (and KT) used Eudora. Even tho' this is not a DTP app, I just trust you guys--maybe it's the "we're all creative pros" thing?!

My Eudora is my life blood. I use it like a database for ALL of my correspondence and even sometimes entering data in as an "email" to myself just to keep it in my Eudora "database" for later reference.
1. I need multiple mailboxes (I presently use 150 different mailboxes)
2. I need filtering that I can write/define for my...
3. 17-20 different email addresses as they all come in.

My filters right now number about 40.
ie: If mail is TO: "xyz@kassj.com", and Subject: has "keyword" included, then put it in "THISmailbox."

I manage so many different businesses/clients that this sorting/filtering/storage is a deal-breaking issue for me. I am sure I can now whittle my mailboxes down by MAYBE half, but probably no more than that. I really rely on my Eudora for when I have to go back in time to find some info.

Any suggestions are sure welcome.

tia, kass