There are some use cases when using `reject_unverified_recipient`
(http://www.postfix.org/postconf.5.html#reject_unverified_recipient)
doesn't seem to be as good idea. This patch fixes this.
While in theory it seems good, in practice (for our use case) it's not:
- the service cannot send out emails as fast, as each "RCPT TO" will
result in a DNS lookup (and connection to the target server), which can
slow things down considerably.
- the target server might just be busy or temporarily offline. This will
prevent the service from sending out the email, which defeats the
purpose of mail bagging.
- we might be behind a firewall and not even be able to connect to the
target server for email validation
Furthermore, this patch include the following line:
`smtpd_relay_restrictions = permit`
This basically opens up relay functionality to any address. Previously
there was an issue if you wanted to send an email to the address which
was listed in the `$ALLOWED_SENDER_DOMAINS`.
hosts's username and password, if your remote host requires
authentication.
NEW FEATURE: The possibility to execute third party scripts. This should
make extending this image easier.
REFACTORING: Dockerfile now starts with run.sh instead of suprevisor.
This makes it much easier to see any errors that might creep into the
code. Also note that the script now relies on POSIX-compliant commands
only so the executor has been changed from /bin/bash to /bin/sh.
