Different SMTP relays for different domains in postfix

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?

 

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 ...

 

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]assword
(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