Add and configure mu4e to read/send emails from emacs.

The mu4e package was installed through debian apt, I
have to find a way to manage it with straight.el

elisp/mu4e-setup.el

@@ -0,0 +1,36 @@
+;; Largely based on ... and ...
+;; use mu4e for e-mail in emacs
+(setq mail-user-agent 'mu4e-user-agent)
+
+;; Set the root maildir
+(setq mu4e-maildir "~/.mail")
+
+;; some other dirs
+(setq mu4e-sent-folder "/posteo/Sent"
+      mu4e-drafts-folder "/drafts")
+
+;; a  list of user's e-mail addresses
+(setq mu4e-user-mail-address-list '("mprodrigues@posteo.net"))
+
+;; the headers to show in the headers list -- a pair of a field
+;; and its width, with `nil' meaning 'unlimited'
+;; (better only use that for the last field.
+;; These are the defaults:
+(setq mu4e-headers-fields
+    '( (:date          .  25)    ;; alternatively, use :human-date
+       (:flags         .   6)
+       (:from          .  22)
+       (:subject       .  nil))) ;; alternatively, use :thread-subject
+
+;; general emacs mail settings; used when composing e-mail
+;; the non-mu4e-* stuff is inherited from emacs/message-mode
+(setq mu4e-compose-reply-to-address "mprodrigues@posteo.net"
+      user-mail-address "mprodrigues@posteo.net"
+      user-full-name  "Mateus P. Rodrigues")
+
+;; SMTP configuration
+(setq message-send-mail-function 'smtpmail-send-it
+      user-mail-address "mprodrigues@posteo.net"
+      smtpmail-default-smtp-server "posteo.de"
+      smtpmail-smtp-server "posteo.de"
+      smtpmail-smtp-service 587)