On 6/7/2013 11:28 AM, Noel Jones wrote: > Generally only internal systems and spammers use IP literals for the > HELO hostname. I wouldn't recommend it.
Absolutely. > I would suggest not using "123-243-137-139.static.tpgi.com.au" as > your HELO, since that's what all the spam bots do. Some folks will > reject such "generic" HELO names, or mark your mail as spam. Having generic rDNS sucks, but the existence of 'static' in your rDNS string helps a bit. This tends to signify a small biz user or an advanced consumer. > You should use a HELO that makes you look like a mail server, such > as 'mail.example.com' which has a matching A record pointing to your > IP address. Absolutely. > Then have your ISP change your PTR to match the "mail.example.com" > you use as the HELO name. If not possible, some folks may still > reject your mail. If your ISP is like mine and simply does not offer custom rNDS, there are additional things you can do to lessen the chances of being rejected. First, create an SPF record designating only your server IP as allowed to send mail for your domain. Second, register your server IP address with one or more dns whitelist services, such as dnswl.org. Third, configure a TCP 25 egress filter on your edge router to prevent a spambot infection from emitting spam from your NAT'd public IP address. -- Stan
