Notes on Linux PostFix email server

• Aliases configured in

  /etc/postfix/virtual

• compile file in to *.db with postmap

  /usr/sbin/postmap /etc/postfix/virtual

Setup postfix so gmail can send email through your server to use your own domain

• Install sasl
  • apt install libsasl2-modules sasl2-bin

• Tell postfix to use sasldb

  # cat /etc/postfix/sasl/smtpd.conf 
  pwcheck_method: saslauthd

• Debug smtp sasl auth https://wiki.vigor.nz/smtp

• add entries to /etc/postfix/sasl_passwd

  • then compile to db with # postmap sasl_passwd

• Test local user/password with testsaslauthd

  # cat /etc/default/saslauthd
    ... MECHANISMS="sasldb
    ... OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd"
  # # ls -l /etc/sasldb2   <<The sasldb
  # sasldblistusers2
  # saslpasswd2 <user>
  # testsaslauthd -u <user> -p <password> -f /var/spool/postfix/var/run/saslauthd/mux

• Test with openssl s_client

  $ echo -n "<user>" | base64
  $ echo -n "<password>" | base64
  $ openssl s_client -connect vigor.nz:25 -starttls smtp
  EHLO test.com
  AUTH LOGIN
  334 VXNlcm5hbWU6   >> = "Username:" in base64
  <user|base64>
  334 UGFzc3dvcmQ6   >> = "Password:" in base64
  <pass|base64>
  535 5.7.8 Error: authentication failed: authentication failure

Configure gmail email

• Log into gmail
• Click gear top right, Settings, and then all settings

• [Accounts and Import] -> [Add another email address]

• Popup, complete [Name: <description>] [email: <address>], uncheck [ ][Treat as an alias] then [Next >>].

• Complete server details
  • SMTP Server: [smtp.vigor.nz] Port: 25

  • Username: ["<Normally email address, or smtp user>"]

  • Password: ["xxxxxxx"]
  • [x] Secure connection TLS
  • You should then receive a test email from gmail, and just click on the link or copy the code.

• Check tls certificate on smtp server

  # echo "quit" | openssl s_client -starttls smtp -crlf -connect <smtp.host>:25 | openssl x509 -noout -text | grep DNS: