content/blog/mail_server_alpine_postfix_dovecot_tutorial.md: add to dovecot section

content/blog/mail_server_alpine_postfix_dovecot_tutorial.md

@@ -447,7 +447,86 @@ Restart Postfix.
 
 # Dovecot
 
-[Dovecot](https://www.dovecot.org/) is a popular IMAP and POP3 server which we'll be using for our MDA.
+[Dovecot](https://www.dovecot.org/) is a popular IMAP and POP3 server which we'll be using for our MDA. Let's install
+it:
+
+    # apk add dovecot
+
+Check the Dovecot version with:
+
+    $ dovecot --version
+
+Now let's enable IMAP by editing `/etc/dovecot/dovecot.conf`. Find a `protocols = ` line, or add one, and set it to:
+
+```conf
+protocols = imap
+```
+
+## Configure how to store emails
+
+You probably want to use the Maildir format for storing emails, where each user's mail is stored at `~/Maildir` (this
+can be set to another location if desired).
+
+In `/etc/dovecot/conf.d/10-mail.conf`, set:
+
+```conf
+mail_location = maildir:~/Maildir
+mail_privileged_group = mail
+```
+
+`mail_privileged_group` tells us which group of Unix users can send mail; in this case, it's anyone in the `mail`
+group. You can create the group with:
+
+    # addgroup mail
+    # adduser postfix mail
+    # adduser dovecot mail
+
+We want to ensure that `postfix` and `dovecot` users have the right to access mail.
+
+To change the Maildir directory, e.g. to set it to `~/mail`, you would set the following:
+
+`/etc/dovecot/conf.d/10-mail.conf`:
+
+```conf
+mail_location = maildir:~/mail
+```
+
+`/etc/postfix/main.cf`:
+
+```conf
+home_mailbox = mail/
+```
+
+## Get emails with LMTP
+
+<abbr title="Local Mail Transfer Protocol">LMTP</abbr> is a protocol which can be used for Postfix to pass incoming
+emails to Dovecot. To install it for Dovecot:
+
+    # apk add dovecot-lmtpd
+
+Add `lmtp` to the supported protocols in `/etc/dovecot/dovecot.conf`:
+
+```conf
+protocols = imap lmtp
+```
+
+Now change the LMTP service (or add if it isn't already there) in `/etc/dovecot/conf.d/10-master.conf` to:
+
+```conf
+service lmtp {
+  unix_listener /var/spool/postfix/private/dovecot-lmtp {
+    mode = 0600
+    user = postfix
+    group = postfix
+  }
+```
+
+Postfix needs to be configured to use this socket. Edit `/etc/postfix/main.cf` with the following lines:
+
+```conf
+mailbox_transport = lmtp:unix:private/dovecot-lmtp
+smtputf8_enable = no
+```
 
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