This is downvoted but needs to be said. Thunderbird was an amazing 90's style piece of software that has unfortunately been been changed into a more "modern" look, with excessive white space and power-user hostile work flows.

It was near perfect, just needed better search, pretty much.

Exactly. It used to be good and they're making it worse every day.

“90s style” seems to be a compliment in some posts and a negative in others.

Very likely user’s age perspective.

It’s absolutely correct though.