how to get ride of secondary-mx spam-problem?
as you may already have noted, some of these spammers by intention send their load of crap to the secondary-mx, even when primary-mx is online.I cant have spamfilter on secondary-mx, since secondary-mx does not have the user-database available (its only a relay-server).
Now what happens is that secondary-mx accepts the crap (what primary-mx would not do) and trys to deliver it to primary-mx, but primary-mx refuses to accept the spam, so secondary-mx sends out a "can not deliver" error email to the sender-address of that email.
and since this address is of course forged that error-message just comes back as undeliverable, and my secondary-mx mailbox gets filled with them.
And there is also one more problem with this crap as you most likly can immagine.
How do you fix these issues?
I use sendmail as mta.