[kwlug-disc] About spamming techniques [was: Nextcloud 11]

[Hubert Chathi]

On Wed, 14 Dec 2016 15:30:16 -0500, Bob Jonkman <bjonkman at sobac.com> said:

> Jason wrote:
>> If [a spammer] get a notification for blocked messages, [spammer] can
>> iterate parameters until you figure out the exact configuration.

> Even worse, it causes spam backscatter. If a spammer spoofs your email
> address as sender, then when my mail server sends back a delivery
> failure message it'll go to you. It's a clever way for spammers to get
> their mail to you via my spam rejection rules.

Yes, that's why it's better to reject mail at SMTP-time, rather than to
accept mail and then generate a bounce email.  That way, it's the
sender's server who generates the bounce email, and presumably they know
the actual sender.

Allowing servers to send mail on behalf of other people is quite a handy
feature of email (it allows, for example, email lists and forwarders),
but causes spam problems.