How to configure postfix to only send to whitelisted addresses?

Question

I want to configure postfix to only send mail to addresses in a whitelist. I have tried to use smtpd_recipient_restrictions in main.cf like so:

smtpd_recipient_restrictions =
    reject_unauth_destination
    check_recipient_access hash:/path/to/whitelist

The whitelist file is of the format

address@example.com    OK
another@example.com    OK

And then translated into a hash with the postmap command.

Still, the relay is sending mail to non-whitelisted addresses. What am I missing?

Edit: I am sending this mail via the sendmail command, which apparently bypasses the smptd restrictions. Is there a way to deal with this?

Edit 2/The rest of the story: I spent quite a bit of time trying to make sendmail send via SMTP only to discover the command I was using was not sendmail, but postfix's sendmail compatibility interface which mimics functionality but can't be told to use SMTP as far as I could tell.

84104's solution worked perfectly though.

Answer 1

You told postfix to reject some types of mail and accept some other mail. It's possible some messages are not caught be either filter in which case they are permitted. I think you want to tell it to accept (check) only list and reject all else.

smtpd_recipient_restrictions =
    check_recipient_access hash:/path/to/whitelist
    reject

---

in response to edit:
sendmail(1) uses postdrop(1) not smtpd(8) One way to achieve something like what you're looking for is to manipulate transport(5)'s behavior.

main.cf
    transport_maps = hash:/etc/postfix/transport

transport
    address1@domain.tld :
    address2@domain.tld :
    senderaddress@yourdomain.tld :
    * error: Recipient not whitelisted.

Note: If you don't include the sender's address in the transport map it will be unable to receive bounce messages.