You can do it, but you wont acheive anything. A spam filter performing a DNS lookup will not poll for CNAME information. It will look for A, MX, and PTR.
On Wed, May 28, 2008 at 2:15 PM, N Parr <[EMAIL PROTECTED]> wrote: > So then, it would be perfectly fine for me to create a cname alias like > mail.mydomain.com that pointed to mortonrb-pool5-static-4.ispxxx.com and > then point my primary MX at that alias? But what I don't understand is > when the receiving spam filter checks the PTR will they see the alias I > created and think everything matches up or will they see > mortonrb-pool5-static-4.ispxxx.com? > > -----Original Message----- > From: Micheal Espinola Jr [mailto:[EMAIL PROTECTED] > Sent: Wednesday, May 28, 2008 1:04 PM > To: NT System Admin Issues > Subject: Re: Reverse DNS Advice for outbound email > > No, it wouldnt. Spam filters arent interested in CNAME records. They > examine, A, MX, and PTR. > > Once upon a time I actually blogged about this. It may be of help to > you: > > http://www.espinola.net/blog/archives/5 > > > On Wed, May 28, 2008 at 1:53 PM, N Parr <[EMAIL PROTECTED]> > wrote: >> That's exactly my concern and why I thought of it because I have my >> filter set up the same way. Problem is I'm limited on my provider >> choices. A CNAME record wouldn't work for this would it? From what >> I've read it's a bad thing to mix MX with cnames. >> >> -----Original Message----- >> From: Micheal Espinola Jr [mailto:[EMAIL PROTECTED] >> Sent: Wednesday, May 28, 2008 12:46 PM >> To: NT System Admin Issues >> Subject: Re: Reverse DNS Advice for outbound email >> >> I would change providers. There are words in our PTR that can trigger > >> spam filters. Words like, "pool", etc... At least its not based on >> an IP or MAC address, but its still a risk. >> >> >> On Wed, May 28, 2008 at 1:38 PM, N Parr <[EMAIL PROTECTED]> >> wrote: >>> We host our own email and we are changing our primary ISP. Per their > >>> policy they will not change the Reverse DNS of our static IP to be >>> anything other than mortonrb-pool5-static-4.ispxxx.com. I have >>> control of my DNS records and can set that as an MX but I'm kind of >>> worried about some spam filters having issues with such a long DNS >>> name with the word "pool" in it when trying to send mail. Using >>> their >> >>> mail server as a smart host is out of the question because if they go > >>> down our ASA box will automatically fail over to our secondary ISP >>> and >> >>> be unable to connect to their down mail server. Do you think using >>> this long DNS name will cause issues trying to send outbound email. >>> BTW my DNS is hosted with network solutions and they don't support >>> TXT >> >>> records so I can't create an SPF. >>> Thanks >>> Niles >>> >>> ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ >>> ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~ >>> >> >> >> >> -- >> ME2 >> >> ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ >> ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~ >> >> >> ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ >> ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~ >> > > > > -- > ME2 > > ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ > ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~ > > > ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ > ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~ > -- ME2 ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
