Mail backups with local Dovecot

15 Jan 2019

For years I struggled with the right way of backing up my emails - operating systems, devices and mail-programs changed from time to time…

Maybe now I found the best way of doing it right: Use a locally installed Dovecot IMAP-Server storing to Maildir.

Using a server set up only for this purpose allows me do use any frontend to manage the mails (such as Thunderbird, or whatever you like) and at the same time any backup solution (rsnapshot, TimeMachine, BackInTime).
Dovecot can be set up on any UNIX-like OS, so probably I can set it up in the future to and just use the backup of my Maildir.

Here is how I did it on macOS (please also see here), but should be nearly the same on any other OS.

install:

~ % brew install dovecot

adopt config-files

~ % cp -pr /usr/local/Cellar/dovecot/2.3.2.1_1/share/doc/dovecot/example-config/ /usr/local/etc/dovecot/

create /use/local/etc/dovecot/local.conf (shortened a bit, please see post on xdeb.org for a fully commented example):

# A comma separated list of IPs or hosts where to listen in for connections. 
listen = 127.0.0.1

# Protocols we want to be serving.
protocols = imap

# Static passdb.
passdb {
  driver = static
  args = password=VERY_SECRET_PASSWORD
}

# Location for users' mailboxes. 
#   %n - user part in user@domain
mail_location = maildir:/Users/martin/%n


# System user and group used to access mails. If you use multiple, userdb
# can override these by returning uid or gid fields. You can use either numbers
# or names. <doc/wiki/UserIds.txt>
mail_uid = martin
mail_gid = admin

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = no

# Login user is internally used by login processes. This is the most untrusted
# user in Dovecot system. It shouldn't have access to anything at all.
default_login_user = _dovenull

# Internal user is used by unprivileged processes. It should be separate from
# login user, so that login processes can't disturb other processes.
default_internal_user = _dovecot
# Internal group is expected to be the primary group of the default_internal_user.
default_internal_group = mail

# Setting limits.
default_process_limit = 10
default_client_limit = 50

If you want to manage your backup-mails using your mobile phone, you should limit the listen parameter to your home wifi (eg 192.168.0.*).

disable/comment default auth-settings in /usr/local/etc/dovecot/conf.d/10-auth.conf

#!include auth-system.conf.ext

disable/comment default ssl-settings in /usr/local/etc/dovecot/conf.d/10-ssl.conf

#ssl_cert = </etc/ssl/certs/dovecot.pem
#ssl_key = </etc/ssl/private/dovecot.pem

run the dovecot-server (it has to be done as root…)

~ % sudo brew service start dovecot

You can stop the serve with:

~ % sudo brew service stop dovecot

manage your mails

Now you can configure your email-client of choice to point to an IMAP-account to the box you just installed dovecot (127.0.0.1 if its the same machine your client runs on) using any username and the password you set in local.conf.

Backup

The mails should appear inside ~/Maildir and are ready to be backed up.
Any directories created inside of the IMAP-account (using your mail-client) are stored as hidden directories (leading dot), so be sure to backup them too.

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Tags:  backups