Most underrated female recording artists..

Joni Mitchell specifically Hejira. This album features Jaco Pastorious on bass - of course. Beautiful listening. Greg 

Who’s rating this to be qualified for underrating? Never heard before, poor quality, never mentioned in this thread? One of my most favored categories as is with many here. 
I will add, in honor of my Dad, sill alive at 95, was keyboard player for Big Band East on Long Island,  gets goose bumps in his limited hearing when I play, Susan Barrett, LSP-3738. She deserves a listen. Thanks 

I would add Nina Simone to your list.

The list is large, but here are a few of my favorites:

Linda Thompson - (ex of Richard Thompson) Dreams Fly Away

Laura Nyro - Eli and the Thirteenth Confession

Allison Russell - (no kin) with Quantic- Look Around the Corner

Emmylou Harris - Wrecking Ball

Dusty Springfield- Dusty in Memphis

Nanci Griffith- The Complete MCA Studio Recordings

Karla Bonoff- All My Life: the best of

Patty Griffin- Servant of Love

That’s a good start….

There are so many you can't count them. Many made a small living putting out a few albums and singing at coffee houses. Here's a few of my favorites that are undervalued:

Bonnie Koloc - when she was a young a voice that could soar from one note to another effortlessly.

Priscilla Herdman - a voice like an angel. Her version of 'And The Band Played Waltzing Matilda' an anti war song is chilling due to the contrast of the words and her angelic voice.

Jo Ann Kelly - the best white blues singer I've heard. She actually sounds black.

June Tabor - awesome sense of timing

Mary McCaslin - small voice that just grows on you. Wrote songs that bare her soul.

Sandy Denny - well known but I believe under rated both as a brilliant singer and song writer.