On Sun, 15 Jan 2012 23:50:02 +0200, Mark Sapiro <[email protected]> wrote:
On 11:59 AM, Charles Marcus wrote:
On 2012-01-14 12:23 PM, IVO GELOV (CRM) <[email protected]> wrote:
I have downloaded the latest version 4.0 - but it seems there is no
way to prevent spammers to use forged email addresses. I decided to
remove the vacation feature from our corporate mail server, because
it actually opens a backdoor (even though only when someone decides
to activate his vacation auto-reply) for spammers and puts a risk on
the company (our server can be blacklisted).
Sorry, I misread your message...
However, (I *think*) there *is* a simple solution to your problem, if I
now understand it correctly...
Simply disallow anyone sending from an email address in your domain from
sending without SASL_AUTHing...
I don't see how this will help. The scenario the OP is concerned about
is [email protected] sends a message with forged From: and maybe
envelope sender [email protected] to his user on vacation. The
vacation program sends an autoresponse to the victim.
However, why worry about this minimal backscatter? A good vacation
program will not send more that one autoresponse per long time (a week?)
for a given sender/recipient and won't include the original spam
payload. So, even though a spammer might use this backdoor to cause your
server to send messages to multiple recipients, the messages should not
have spam payloads and shouldn't be sent more that once to a given end
recipient.
The limitation of 1 message per week for any unique combination of
sender/recipient
does not stop backscatter - because each message can come with a new forged
FROM address,
and from different compromised mail servers.
The spammer does not have control over the body of the auto-replies (which is
something
like "I am not at the office, please write to my colleagues"), but it still
may cause the victims to take some measures.
