Postfix Configuration Howto

This Howto has been written for Debian GNU/Linus distribution

Check you have postfix, libsasl2, libsasl2-modules, openssl packages installed correctly

Most of the files mentioned should already be there and you should be able to edit them easily. If a file does not exist you can create it with the command touch filename for files and mkdir directoryname for directories.

In the following howto USER should be changed in the username of the user you login with on your computer, while ADDRESS@DOMAIN.ORG should be changed in your full A/I mailbox address. PASSWORD should be changed in your mailbox password.

The file you’ll need to edit for successfully sending email through A/I servers using postfix are the following ones.

/etc/aliases file

Check it contains the following line

root:   USER

If it does not, add it and then run the command:

# postalias /etc/aliases

/etc/postfix/sender_canonical file

Add the following lines:

root    ADDRESS@DOMAIN.ORG
USER   ADDRESS@DOMAIN.ORG

Then run:

# postmap /etc/postfix/sender_canonical

/etc/postfix/virtual file

All the mail addresses you download via fetchmail should be pointing at your login user on your computer.

ADDRESS@DOMAIN.ORG      USER
giovanni@alice.it       USER
... ecc. ....           USER

Then run:

# postmap /etc/postfix/virtual

/etc/postfix/sasl_pwd file

Add the following line, but be aware that this means that your password will be stored in plain text in your filesystem. However this is the only way to use postfix to send email through postfix.

smtp.autistici.org [ tab ] ADDRESS@DOMAIN.ORG:PASSWORD

Then run:

# postmap /etc/postfix/sasl_pwd

Certificates

Install the ca-certificates package

Postfix Keys

Create a file named random_file in the /etc/postfix/ssl directory.

In the file type in 2-3 lines of random digits (just hit your keyboard at random). Then run the following command:

# openssl genrsa -rand random_file -out chiave-privata.pem 1024

Rename the new chiave-privata.pem file and copy it in /etc/postfix/ssl/postfix-key

Create /etc/postfix/tls-sites file

Edit the file and add the following line:

smtp.autistici.org [ tab ] MUST

Main Postfix configuration

Now we are almost done.

Edit the /etc/postfix/main.cf file and add the following lines at the end of the file

relayhost = [smtp.autistici.org]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_pwd
smtp_sasl_mechanism_filter = plain, login
smtp_sasl_security_option =
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_tls_key_file = /etc/postfix/ssl/postfix-key
smtp_use_tls = yes
smtp_tls_per_site = hash:/etc/postfix/tls-sites
smtp_tls_loglevel = 1
smtp_sasl_tls_security_options = noanonymous
# EOF

Note: if you are already using postfix to send your email remember to comment out the relayhost line you were using until configuring your server for A/I.

After each change in the previous file it’s mandatory to run the followin postalias or postmap command.

Once you are finished with the /etc/postfix/main.cf file, run the following command and you are done

# postfix reload

Postfix logfiles

If you want to check if postfix is sending email or what kind of errors it is encountering, once your mail has been sent you can check the logfile

# less /var/log/mail.log

Thanks to rainbow for this howto