Mailroom

Mailroom is a privacy-conscious desktop app for reclaiming mailbox space.
It scans your mailbox on your own machine — reading only the envelope
(sender, size, date) plus attachment names, types and sizes, never the
message body or file contents — shows you exactly what is taking up space,
and helps you tidy it with your say-so on every delete. Yahoo Mail today.

Your mail and password stay on your device. Only your email address is sent
— to run your licence and, unless you opt out, email you trial reminders and
occasional product news.