Postfix SMTP authentication per domain

postfixsmtpsmtp-auth

Is it possible to configure SMTP authentication on Postfix with different user/pass credentials for different domains?

So, I have a MTA that relays emails from ~20 different domains. When sending emails to a specific domain, say example.com, my MTA has to authenticate. No problem, this solved the problem:
http://postfix.state-of-mind.de/patrick.koetter/smtpauth/smtp_auth_mailservers.html

But, I have a different account for every sender domain. So, when mydomain1.com sends email to example.com, it uses one account. Another one for mydomain2.com -> example.com etc.

Is this achievable through Postfix?

Best Answer

You should read up a bit on this option: smtp_sender_dependent_authentication, with that, and two other related DB mappings, sender_dependent_relayhost_maps, and smtp_sasl_password_maps, you can create per sender password entries.

In the sender_dependent_relayhost maps, you map username@domain [smtp_host], and in the smtp_sasl_password maps, you map email user:password or domain user:password(whatever those might be). These are classic postfix lookup tables, they can be in mysql, dbm, hash, etc.

With a combination of mysql and some duplication, you could quite possibly do what you want.

You could make a table with 4 fields, email, smtp_relay, user, password, then have postfix look up the email and smtp_relay for the sender_dependent_relay_maps, then email user:password for smtp_sasl_password_maps. This would have to be populated with each email address that has to relay, each server that you relay through, and each user:password combo for the authentication.

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I believe this is what you want.

http://www.postfix.org/ADDRESS_REWRITING_README.html#generic

Example:

/etc/postfix/main.cf:
    smtp_generic_maps = hash:/etc/postfix/generic

/etc/postfix/generic:
    his@localdomain.local       hisaccount@hisisp.example
    her@localdomain.local       heraccount@herisp.example
    @localdomain.local          hisaccount+local@hisisp.example

So, if you have postfix installed and configured already.

Open main.cf and add the generic maps setting above.

Then open the generic file and add @example.com @example2.com or whatever settings you need for your environment

This is a hash file so when you are done run postmap /etc/postfix/generic

Then restart postfix.

UPDATE

It looks like this is actually what you are after.

edit the master cf file and change this line

smtp inet n - n - - smtpd

To:

localhost:smtp  inet n - n - - smtpd
ipaddress1:smtp inet n - n - - smtpd
ipaddress2:smtp inet n - n - - smtpd -o myhostname=hostname2
.
.
.
ipaddressn:smtp inet n - n - - smtpd -o myhostname=hostname3

restart postfix

Obviously this will require you to setup multiple IP address, one for each domain and setting up the reverse DNS etc. I believe this is the only way to do this.

Postmap: fatal: open database /etc/postfix/sasl_passwd.db: Permission denied

You need to make sure that postfix user is able to read that file. You can post the output of $ sudo ls -l /etc/postfix/sasl_passwd.db to get more help.

To create this file, you can use the command:

$ sudo postmap sasl_passwd

This will create the .db file.

Best Answer

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Postmap: fatal: open database /etc/postfix/sasl_passwd.db: Permission denied

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