Good day,
So I am somewhat green when it comes to how mail gateways manage email.
After finding that my own mail setup at home has caught almost 5000 spam mails
in less than a month I have finally thrown my hands in the air and wanted to
hopefully get some understanding from this list.
The amount alone is huge I think when I am only hosting my wife and myself (as
well as the usual abuse etc. contacts).
I am worried that my home is an open relay in a manner I have not found.
Then I learn that via telnet I can send email from mydomain.com to mydomain.com
and have it delivered even when the telnet session is from a public IP.
So, I am a little fuzzy on what it is I am trying to learn here, but:
1. Would you think 5000 emails a month with maybe 200 valid emails is normal in
a home/family type setup?
2. Is mail always accepted and relayed when the sender and recipient domain is
the same? (This is without sender authentication configured or capability).
a. If yes, what is to stop an angry neighbor on his vacation to China
from sending a nasty email from me to my wife? (In this unsecure setup).
b. My gateway at home (Smoothwall using DSPAM/SEMF? mod) only accepts
the initial HELO if followed by connecting domain name (HELO domain.com) So how
come I can connect from domainx.com and send email from domainy.com to
domainy.com?
c. What can I do to remove this risk?
3. Any recommendations on a free mail gateway solution? SpamAssassin? ClamAV?
My goal is to migrate away from Exchange 2003. I have been wanting to try
Zimbra for mail server but would like a good mail gateway in the DMZ instead of
hosted by the firewall.
Thank you and I will follow up with answers to questions for clarification.
Nick Vaernhoej
"Quidquid latine dictum sit, altum sonatur."
This electronic transmission is intended for the addressee (s) named above. It
contains information that is privileged, confidential, or otherwise protected
from use and disclosure. If you are not the intended recipient you are hereby
notified that any review, disclosure, copy, or dissemination of this
transmission or the taking of any action in reliance on its contents, or other
use is strictly prohibited. If you have received this transmission in error,
please notify the sender that this message was received in error and then
delete this message.
Thank you.
