Dovecot

Liens

• Dovecot wiki
• Dovecot on Ubuntu

Commands

# display the current configuration dovecot -n

Protocols

/etc/dovecot/dovecot.conf

# Enable installed protocols !include_try /usr/share/dovecot/protocols.d/*.protocol

/usr/share/dovecot/protocols.d/imapd.protocol

protocols = $protocols imap

Mailboxes

/etc/dovecot/conf.d/10-mail.conf

# use maildir mail_location = maildir:~/maildir

Authentication

/etc/dovecot/conf.d/10-auth.conf

# Disable plaintext authentications unless SSL/TLS is used or if you connect from localhost disable_plaintext_auth = yes # Space separated list of wanted authentication mechanisms: # plain login digest-md5 cram-md5 ntlm rpa apop anonymous gssapi otp skey gss-spnego # NOTE: plain: envoie du mot de passe non-encrypté. Dans le cadre d'une connexion SSL/TLS ce n'est pas un problème. auth_mechanisms = plain

System users

By default, dovecot use system users and their passwords to connect.

/etc/dovecot/conf.d/10-auth.conf

# use system users !include auth-system.conf.ext

/etc/dovecot/conf.d/auth-system.conf.ext

passdb { driver = pam # use /etc/pam.d/imap for IMAP args = %s } userdb { driver = passwd }

/etc/pam.d/imap

# allow IMAP access only for users in /etc/imapusers file auth required pam_listfile.so item=user sense=allow file=/etc/imapusers onerr=fail

/etc/imapusers

user1 user2

• Restrict Access

Passwd-file

/etc/dovecot/conf.d/10-auth.conf

# use non-system users with passwd-file !include auth-system.conf.ext

/etc/dovecot/conf.d/auth-passwdfile.conf.ext

passdb { driver = passwd-file args = scheme=SHA512-CRYPT username_format=%u /etc/dovecot/users } userdb { driver = passwd-file args = username_format=%u /etc/dovecot/users }

/etc/dovecot/users

# password only user:{SHA512-CRYPT}pass # password + user user:{SHA512-CRYPT}pass:1000:1000::/home/user::userdb_mail=maildir:~/maildir allow_nets=192.168.0.0/24

# generate an encrypted password doveadm pw -s SHA512-CRYPT # check the hash match the password doveadm pw -V -t '{SHA512-CRYPT}hash' # list available password schemes doveadm pw -l

• How to make dovecot password independent of server password?
• How do I change Dovecot virtual user passwords?
• Password Schemes
• Allow_nets extra field

SASL client authentication

Needed configuration to use dovecot with postfix.

/etc/dovecot/conf.d/10-master.conf

service auth { # Postfix smtp-auth unix_listener /var/spool/postfix/private/auth { mode = 0666 } }

/etc/dovecot/conf.d/10-auth.conf

# add the login authentication mechanism auth_mechanisms = plain login

TLS

/etc/dovecot/conf.d/10-ssl.conf

ssl = required ssl_cert = </etc/letsencrypt/live/domain.fr/fullchain.pem ssl_key = </etc/letsencrypt/live/domain.fr/privkey.pem

IMAP Compression

/etc/dovecot/conf.d/20-imap.conf

protocol imap { mail_plugins = $mail_plugins imap_zlib # imap_zlib: reduce the bandwidth usage of IMAP }

Test

# imap telnet localhost imap2 # OK * DOVECOT * READY A1 LOGIN username password # LOGGED IN A2 LIST "" "*" A3 EXAMINE INBOX A5 LOGOUT # imaps openssl s_client -connect mail.domain.fr:993

Debug

/etc/dovecot/conf.d/10-logging.conf

# Log unsuccessful authentication attempts and the reasons why they failed. auth_verbose = yes # Even more verbose logging for debugging purposes. auth_debug = yes # In case of password mismatches, log the passwords and used scheme so the # problem can be debugged. Enabling this also enables auth_debug. auth_debug_passwords = yes

Log

• /var/log/mail.err

Application Android

• Blue Mail

Configuration

• Serveur IMAP: mail.domain.fr
• Sécurité: STARTTLS
• Authentification: PLAIN
• Port: 143
• Serveur SMTP: mail.domain.fr
• Sécurité: STARTTLS
• Port: 587
• Authentification: AUTOMATIC

UFW

# allow incoming IMAP (143) to fetch emails sudo ufw allow "Dovecot IMAP" # allow incoming SMTP (587) to submit emails sudo ufw allow "Postfix Submission"

Installation

sudo apt install dovecot-imapd