Different SMTP relays for different domains in postfix

Discussion in 'Installation/Configuration' started by kanour, Sep 1, 2019.

  1. kanour

    kanour Member

    I need to use SMTP relay from mailgun. It seems that I need to use smtp relay credentials for each domain I am hosting separately.

    For example:
    for domainA.com

    relayhost = [smtp.mailgun.org]:587
    smtp_sasl_auth_enable = yes
    smtp_sasl_password_maps = static:[email protected]:password
    smtp_sasl_security_options = noanonymous

    for domainB.com

    relayhost = [smtp.mailgun.org]:587
    smtp_sasl_auth_enable = yes
    smtp_sasl_password_maps = static:[email protected]:password
    smtp_sasl_security_options = noanonymous


    Any advice on how to achieve this in Postfix? Or is there any other SMTP relay provide who I can send emails through one relay account for multiple domains and they will relay it appropriately?
     
    Last edited: Sep 1, 2019
  2. Steini86

    Steini86 Member

    Attention, the following is untested

    As far as I understood, you want to set up the relay transports in ispconfig mail -> email routing.
    Then modify your postfix config main.cf:
    Code:
    smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
    Use per domain credentials in /etc/postfix/sasl_passwd
    Code:
    @domain1.com         userA:passwordA
    @domain2.com         userB:passwordB
    
    Don't forget a "postmap hash:/etc/postfix/sasl_passwd" before postfix restart.
    Have never tried it, though ...
     
    kanour likes this.
  3. kanour

    kanour Member

    Hi,
    This is full solution for mailgun.

    To configure Postfix
    /etc/postfix/main.cf
    Code:
    smtp_sasl_auth_enable = yes
    smtp_sasl_security_options = noanonymous
    smtp_sender_dependent_authentication = yes
    smtp_sasl_password_maps = hash:/etc/postfix/smtp_sasl_passwd
    sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay
    
    The smtp_sasl_password_maps file contains a mapping of all domains to the appropriate SMTP credentials. The syntax must be as follows:
    /etc/postfix/smtp_sasl_passwd
    Code:
    @<domain> <smtp_user>@<domain>:<smtp_password>
    @<domain> <smtp_user>@<domain>:<smtp_password>
    
    Example:
    @test.com [email protected]:password
    (the username and password is provided by SMTP relay provider, in this case mailgun)

    The sender_dependent_relayhost_maps file contains a mapping of all domains to the appropriate relay. This option is not necessary if you are using a single relay. The syntax must be as follows:
    /etc/postfix/sender_relay
    Code:
    @<domain> <relay>
    @<domain> <relay>
    
    Example:
    @test.com [smtp.mailgun.org]:587

    After you configure the above run:
    Code:
    postmap /etc/postfix/smtp_sasl_passwd
    postmap /etc/postfix/sender_relay
    systemctl restart postfix
    
     
    Steini86 likes this.

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