Re: AW: [suse-security] sendmail, avoiding open relay

"Jens Hoja" <newsletter@dweb-data.de> writes:

Smtp has no authentication mechanism, but pop has. after configured pop-before-smtp with sendmail only users with authenticated by pop first are allowed to send email through your mailserver.

Sorry, but SMTP does have an authentication mechanism. RFC2554 (and possibly others) describe this. SuSE sendmail supports this, you may have to use package sendmail-sasl rather than just 'plain' sendmail in some releases. This does, of course, need to configured as to what authentication is required.