[lug] Relay attacks

[Rob Nagler]

Every day, the same people try to relay via my machines:

g9EBYlT30225: ruleset=check_rcpt, arg1=<china9988 at 21cn.com>, relay=[61.79.86.193], reject=550 5.7.1 <china9988 at 21cn.com>... Relaying denied. IP name lookup failed [61.79.86.193]
g9EEqbT03558: ruleset=check_rcpt, arg1=<china9988 at 21cn.com>, relay=[210.221.154.23], reject=550 5.7.1 <china9988 at 21cn.com>... Relaying denied. IP name lookup failed [210.221.154.23]
g9EExCT03757: ruleset=check_rcpt, arg1=<nongayrich at runbox.com>, relay=24-90-190-122.nyc.rr.com [24.90.190.122], reject=550 5.7.1 <nongayrich at runbox.com>... Relaying denied
g9F1qWT22634: ruleset=check_rcpt, arg1=<testman100 at hotpop.com>, relay=adsl-157-199-220.dab.bellsouth.net [66.157.199.220], reject=550 5.7.1 <testman100 at hotpop.com>... Relaying denied

Don't they ever give up?  They seem to hit all machines with open SMTP
ports.  It's not really a big deal, but I'm a paranoid sort.  There
must be millions of open SMTP ports on the Internet.  They can't pick
them all everyday, can they?

Just curious,
Rob