Creative Spammers finding out valid accounts on my mail server!

[Michal Vymazal]

Adam Jackson wrote:

> Hi everybody,
> I run a mail server that handles mail for multiple domains. Somehow, a
> spammer is obtaining a list of valid mail accounts on my sendmail server
> and addressing his spam messages to only those accounts. Many of these
> accounts mail accounts have never been used by a person and are not posted
> around the internet anywhere, which leads me to believe there is a way for
> an outsider to query my mail server for a list of valid mail accounts.
> Has anyone heard of this?
> 
> Thank you in advance!
> Adam

Hello Adam
Yes, it's current situation :-(
Which MTA are you using? Sendmail, postfix or qmail? If you are using 
sendmail, try to switch on the parameter access in sendmail.mc

FEATURE(`access_db')dnl

After this, you have to recompile the sendmail scripts and set up the access 
table.

Have a nice day.
-- 
Michal Vymazal
gandalf na mbox.vol.cz
Office Computer