Do you obfuscate email headers when reporting spam issues to clients?
dclements at gmail.com
Wed Nov 6 22:09:19 UTC 2013
On Wed, Nov 6, 2013 at 4:45 PM, William Herrin <bill at herrin.us> wrote:
> Incidentally, I'd suggest that an ounce of prevention is worth a pound
> of cure. Simply block outbound tcp port 25 for new hosting customers
> on a "tell me if you want it open" basis.
Or to thwart those clever spammers, block inbound SYN/ACK packets with a
source port of 25. This catches the ones who send SYNs out other providers
with your network's source addresses which bypasses most simple ACLs.
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