Dovecot

root@mail:~#  apt-get  -y install dovecot-core dovecot-pop3d dovecot-imapd dovecot-lmtpd 

root@mail:~#  vi /etc/dovecot/dovecot.conf

Instruction 1: !include_try local.conf

Instruction 2: protocols = pop3 pop3s imap

# line 30 : uncomment

listen = *, ::

root@mail:~#  vi /etc/dovecot/conf.d/10-auth.conf

# line 10 : uncomment and change (allow plain text auth)

disable_plaintext_auth = no

# line 100 : add

auth_mechanisms = plain login

root@mail:~# vi /etc/dovecot/conf.d/10-mail.conf

# line 30 : change to Maildir

mail_location = maildir:~/Maildir

root@mail:~#   vi /etc/dovecot/conf.d/10-master.conf

# line 110-112 : uncomment and add

 # Postfix smtp-auth

  }

 --------------------------------------------------

Enable protocols

Open # vi /etc/dovecot/conf.d/20-imap.conf and   # vi /etc/dovecot/conf.d/20-pop3.conf and verify:

protocols = imap pop3

root@mail:~#     systemctl restart dovecot 

Mar 24 09:06:05 mail dovecot: imap(habib1@worldcm.net): Fatal: master: service(imap): child 4736 returned error 83 (Out of memory (service imap { vsz_limit=256 MB }, you may need to increase it) - set CORE_OUTOFMEM=1 environment to get core dump)

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

Postfix, Dovecot, and SpamAssassin

Update the package lists and install Postfix, Dovecot, SpamAssassin, and spamc:

sudo apt update# 

apt-get install postfix dovecot-imapd dovecot-pop3d spamassassin spamc

Step 2: Enable and start the SpamAssassin service

Enable the SpamAssassin service to start automatically at boot, and then start the service:

systemctl enable spamassassin

systemctl start spamassassin

Step 3: Configure SpamAssassin settings

Edit the SpamAssassin configuration file /etc/spamassassin/local.cf using a text editor (e.g., nano or vim):

vi  /etc/spamassassin/local.cf

Add or modify the following settings in the file:

These settings will mark emails with a spam score of 5.0 or higher by adding "[SPAM]" to the subject. You can adjust the required_score value as needed. Save the changes and exit the editor.

Step 4: Configure Postfix to use SpamAssassin

Edit the Postfix configuration file /etc/postfix/master.cf:

vi  /etc/postfix/master.cf

Add the following lines to the end of the file:

Save the changes and exit the editor.

Step 5: Restart Postfix

Restart the Postfix service to apply the changes:

systemctl restart postfix

Step 6: Configure Dovecot

Edit the Dovecot configuration file /etc/dovecot/conf.d/90-sieve.conf:

#  nano /etc/dovecot/conf.d/90-sieve.conf

Uncomment or add the following lines:

Save the changes and exit the editor.

Create a default Sieve script /etc/dovecot/sieve/default.sieve:

#  nano /etc/dovecot/sieve/default.sieve

Add the following content to the file:

This script will automatically move messages marked as spam to the "Junk" folder. Save the changes and exit the editor.

Compile the Sieve script:

 sievec /etc/dovecot/sieve/default.sieve

 systemctl restart dovecot

SpamAssassin will now automatically process incoming emails on your server and mark them as spam based on your configuration. The Dovecot Sieve script will move the messages marked as spam to the "Junk" folder for each user. You can further refine the configuration by editing /etc/spamassassin/local.cf and adjusting the settings as needed.