Allow `allowed_users` without TLS when listening 127.0.0.1

[Necoro]

I want to use smtprelay with allowed_users when it is running on a server listening on 127.0.0.1. As there is no incoming network connection, I don't use TLS. Unfortunately, this is blocked by smtprelay:

Local authentication (via allowed_users file) not allowed with non-TLS listener address=127.0.0.1:25

I understand the general rationale, but imho for 127.0.0.1 (and ::1) it should also be allowed. Alternatively, have a config option that allows to override this behavior.

Reason for enabling allowed_users: As the service sends emails via my mail account, I want to control strictly which services can send.

[DuCun]

Perhaps we could try using a self-signed certificate.

[Necoro]

Nah, I explicitly don't want that because the lack of official signing might lead to problems downstream.

[Necoro]

sigh The underlying smtpd-library has the same requirement.

[decke]

Yeah, this also seems to be a smtpd problem.

chrj/smtpd#19