RE: Sendmail 8.11 configuration/security issue

[<john65 () pobox com>]

I think the original sender and several of the respondents may be
confusing 'spam with forged headers' with 'open relaying.'

The original question was not about his relay being hijacked to send
spam, it was about mail coming IN to his company xyz.com for joe () xyz com
purporting to be from another sender at xyz.com when it really came from
somewhere else. That's NOT open relaying, that's forging headers and
there's not much you can do about it without breaking things (What if
mary () xyz com wants to use her xyz.com return address when she's sending
mail from home to joe () xyz com via her local ISP dialup -- Why would you
want to block that?) What's the difference if incoming spam has one
forged address or another anyway? It's still spam!

'Switching to Postfix', using a 'content security gateway,' or 'TLS' are
not going to solve this problem (forging of email headers).