nanog mailing list archives
Re: Do you obfuscate email headers when reporting spam issues to clients?
From: Doug Clements <dclements () gmail com>
Date: Wed, 6 Nov 2013 17:09:19 -0500
On Wed, Nov 6, 2013 at 4:45 PM, William Herrin <bill () 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. --Doug
Current thread:
- Do you obfuscate email headers when reporting spam issues to clients? Landon (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? William Herrin (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? William Herrin (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Doug Clements (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Jimmy Hess (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Jon Lewis (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Rich Kulawiec (Nov 07)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Blake Dunlap (Nov 07)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Nonaht Leyte (Nov 07)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Landon (Nov 12)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Rich Kulawiec (Nov 07)
- Re: Do you obfuscate email headers when reporting spam issues to clients? William Herrin (Nov 07)
- <Possible follow-ups>
- Re: Do you obfuscate email headers when reporting spam issues to clients? Anne P. Mitchell, Esq. (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? William Herrin (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? Anne P. Mitchell, Esq. (Nov 06)
- Re: Do you obfuscate email headers when reporting spam issues to clients? William Herrin (Nov 06)