First you need to install and configure the himalaya CLI. Then you can install this plugin with your favorite plugin manager. For example with vim-plug, add to your .vimrc:

Plug 'soywod/himalaya', {'rtp': 'vim'}

Then:

:PlugInstall

Usage

List messages view

:Himalaya

Function	Default binding
Change the current mbox	`gm`
Show previous page	`gp`
Show next page	`gn`
Read focused msg	`<Enter>`
Write a new msg	`gw`
Reply to the focused msg	`gr`
Reply all to the focused msg	`gR`
Forward the focused message	`gf`
Download all focused msg attachments	`ga`

They can be customized:

nmap gm   <plug>(himalaya-mbox-input)
nmap gp   <plug>(himalaya-mbox-prev-page)
nmap gn   <plug>(himalaya-mbox-next-page)
nmap <cr> <plug>(himalaya-msg-read)
nmap gw   <plug>(himalaya-msg-write)
nmap gr   <plug>(himalaya-msg-reply)
nmap gR   <plug>(himalaya-msg-reply-all)
nmap gf   <plug>(himalaya-msg-forward)
nmap ga   <plug>(himalaya-msg-attachments)

List mailboxes

Default behaviour (basic prompt):

With telescope support:

With fzf support:

Read message view

Function	Default binding
Write a new msg	`gw`
Reply to the msg	`gr`
Reply all to the msg	`gR`
Forward the message	`gf`
Download all msg attachments	`ga`

They can be customized:

nmap gw <plug>(himalaya-msg-write)
nmap gr <plug>(himalaya-msg-reply)
nmap gR <plug>(himalaya-msg-reply-all)
nmap gf <plug>(himalaya-msg-forward)
nmap ga <plug>(himalaya-msg-attachments)

Write message view

When you exit this special buffer, you will be prompted 4 choices:

Send: sends the message
Draft: saves the message into the Drafts mailbox
Quit: quits the buffer without saving
Cancel: goes back to the message edition