SMTP Postfix server in docker-compose

start

• cd config/certs/ && openssl req -new -nodes -keyout smtp.key -out smtp.csr
• cd ../../ && opendkim-genkey -D /etc/opendkim/domainkeys -d example.com -s mail`
  • opendkim-genkey -D ./config/opendkim/ -d $(hostname -d) -s $(hostname)`
• docker-compose up -d
• if don't need DKIM:
  • docker-compose exec postfix bash
  • comment following strings in /etc/postfix/main.cf

  milter_protocol = 2
  milter_default_action = accept
  smtpd_milters = inet:localhost:12301
  non_smtpd_milters = inet:localhost:12301
  

  • docker-compose restart postfix

DNS config

• add A record:
  • mail A
• add MX record:
  • @ MX 10 mail
• add CNAME records:
  • relay CNAME mail
  • smtp CMANE mail
• SPF config:
  • (SPF config in panel example.com. IN TXT "v=spf1 +a +mx ?all")
  • add TXT SPF record
    • example.com. IN TXT "v=spf1 +a +mx ?all"
• DKIM config:
  • (activate in panel)
  • add TXT record:
    • mail._domainkey TXT <from file ./config/opendkim/mail.txt>
  • if needed - add ADSP (for deny other servers receive mails without sign, with my domain): #OLD
    • _adsp._domainkey IN TXT "dkim=all"
• check:
  • dig A mail.example.com
  • dig MX mail.example.com
  • dig TXT mail.example.com
  • dig CNAME mail.example.com
• verify domain in Google:
  • https://support.google.com/a/answer/183895
• spam check:
  • https://spamcheck.postmarkapp.com/
  • https://spamassassin.apache.org/

check mail

• genegate auth for telnet:

  • `perl -MMIME::Base64 -e 'print encode_base64("[email protected]");'
    • dXNlckBzZXJ2ZXIucnU=
  • `perl -MMIME::Base64 -e 'print encode_base64("PASSWORD");'
    • UEFTU1dPUkQ=

• telnet postfix 25

  Trying 172.18.0.9...
  Connected to postfix.
  Escape character is '^]'.
  220 example.com ESMTP Postfix (Ubuntu)
  

  • helo test

  250 example.com
  

  • auth login

  334 VXNlcm5hbWU6
  

  • dXNlckBzZXJ2ZXIucnU=

  334 UGFzc3dvcmQ6
  

  • UEFTU1dPUkQ=

  235 2.7.0 Authentication successful
  

  • mail from: [email protected]

  250 2.1.0 Ok
  

  • rcpt to: [email protected]

  250 2.1.5 Ok
  

  • data

  354 End data with <CR><LF>.<CR><LF>
  

  • From: [email protected]
  • To: [email protected]
  • Subject: testmail
  • some text
  • .

  250 2.0.0 Ok: queued as B209CA20E1E
  

  • quit