Create mail directory

At first create the directories which are needed for your mail account. For example:

mkdir -p ~/Mails/autistici/

Initialize the mu database

After installing mu4e, initialize the mu database by pointing it to your Mail directory:

mu init --maildir /home/INSERT_USERNAME_HERE/Mails --my-address cashmeresamurai@autistici.org

Then index your emails so they become searchable in Emacs:

mu index

Once indexing is complete, you can use mu4e in Emacs to manage and read your mails.

You can adjust ~/Mails to match your actual mail directory path.

Current configuration

(use-package mu4e
  :straight nil
  :ensure nil
  :config
  
  (setq mu4e-mu-binary (executable-find "mu"))
  (setq mu4e-maildir "~/Mails")
  (setq mu4e-get-mail-command (concat (executable-find "mbsync") " -a"))
  (setq mu4e-update-interval 300)
  (setq mu4e-attachment-dir "~/Downloads")
  (setq mu4e-change-filenames-when-moving t)
  
  (setq mu4e-user-mail-address-list 
        '("cashmeresamurai@autistici.org"
          "cashmere@cashmere.rs"))
  
  (setq mu4e-contexts
        `(,(make-mu4e-context
            :name "autistici"
            :match-func
            (lambda (msg)
              (when msg
                (string-prefix-p "/autistici" (mu4e-message-field msg :maildir))))
            :vars '((user-mail-address . "cashmeresamurai@autistici.org")
                    (user-full-name . "cashmere")
                    (mu4e-drafts-folder . "/autistici/Drafts")
                    (mu4e-sent-folder . "/autistici/Sent")
                    (mu4e-trash-folder . "/autistici/Trash")
                    (mu4e-refile-folder . "/autistici/Archive")))
          
          ,(make-mu4e-context
            :name "cashmere"
            :match-func
            (lambda (msg)
              (when msg
                (string-prefix-p "/cashmere/cashmere" (mu4e-message-field msg :maildir))))
            :vars '((user-mail-address . "cashmere@cashmere.rs")
                    (user-full-name . "cashmere")
                    (mu4e-drafts-folder . "/cashmere/cashmere/Drafts")
                    (mu4e-sent-folder . "/cashmere/cashmere/Sent")
                    (mu4e-trash-folder . "/cashmere/cashmere/Trash")
                    (mu4e-refile-folder . "/cashmere/cashmere/Archive")))))
  
  (setq mu4e-context-policy 'pick-first)
  (setq mu4e-compose-context-policy 'ask)
  
  (setq sendmail-program (executable-find "msmtp"))
  (setq send-mail-function 'sendmail-send-it)
  (setq message-send-mail-function 'sendmail-send-it)
  (setq message-sendmail-envelope-from 'header)
  (setq message-kill-buffer-on-exit t)
  
  (defun mu4e-set-msmtp-account ()
    (if (message-mail-p)
        (save-excursion
          (let* ((from (save-restriction
                         (message-narrow-to-headers)
                         (message-fetch-field "from")))
                 (account
                  (cond
                   ((string-match "cashmeresamurai@autistici.org" from) "autistici")
                   ((string-match "cashmere@cashmere.rs" from) "cashmere/cashmere"))))
            (setq message-sendmail-extra-arguments (list '"-a" account))))))
  
  (add-hook 'message-send-mail-hook 'mu4e-set-msmtp-account))

To synchronize emails up, run the following two commands:

mbsync -a
mu index