"#1. 2 MX records pointing to different names that resolve to the
same IP is odd and pointless.
"
> dig maxboostracing.com mx
;; ANSWER SECTION:
maxboostracing.com. 21475 IN MX 10
mx1.maxboostracing.com.
maxboostracing.com. 21475 IN MX 10
mx2.maxboostracing.com.
> dig mx1.maxboostracing.com A
mx1.maxboostracing.com. 43200 IN A 68.15.54.108
> dig mx2.maxboostracing.com A
mx2.maxboostracing.com. 43200 IN A 68.15.54.108
You could remove both MX records completely, as maxboostracing.com
resolves to 68.15.54.108 too. You can also remove the A record for
mx1 and mx2
"#2 Using DynDNS isn't necessarily unwise ..."
OK if the IP is really static, though you could use a DNS provider
that sounds less dynamic.
"#3. Putting any machine engaging in any form of SMTP behind a
device that performs malicious attacks on basic SMTP functionality
[...] is always a bad idea"
> telnet 68.15.54.108 25
Trying 68.15.54.108...
Connected to 68.15.54.108.
[...wait...]
220 maxboostracing.com ESMTP CommuniGate Pro 5.3.13
For me it now looks OK, you probably removed the ESMTP line from the
PIX.
"#4. If you run a mail server using a public IP whose PTR
resolves to a name in a domain that you don't control and is
obviously constructed from the IP address you will have chronic
delivery problems, some of them silent.
"
> dig -x 68.15.54.108
;; ANSWER SECTION:
108.54.15.68.in-addr.arpa. 21599 IN PTR
wsip-68-15-54-108.ri.ri.cox.net.
Here you have a problem. The PTR must be maxboostracing.com or
something.maxboostracing.com. Since your IP is static, ask your ISP
to provide you a valid PTR record. You usually cannot set that up
yourself, and certainly not in your own DNS server.
Nicolas Hatier
On 2014-04-04 11:22, bob wrote:
Hi
Bill, thanks for your reply. See below inline:
On 4/4/2014 11:09 AM, Bill Cole wrote:
On 4 Apr 2014, at 9:28, Bob wrote:
Hello.
Im running 5.3.13 on windows, 32 bit. Every once in a while I
check my server against mxtoolbox, an today I found SMTP
reverse DNS mismatch. My WAN IPV4 address is correct under
settings/network showing my correct external ip address. Do I
need to change something else?
Everything seems to work, just pretty slowly (more on that
later) :)
Thanks for any tips.
I don't track all of the details of MXToolbox's tests, but a few
things seem likely to be causing trouble for maxboostracing.com:
1. 2 MX records pointing to different names that resolve to the
same IP is odd and pointless.
If I do an nslookup on my domain I do see the address be resolved
correctly. I also see it time out 3 times first though, But I
might blame local resolvers for that? Where do you see that
issue?
2. Using DynDNS isn't necessarily unwise
for a domain that handles email, but if your address is actually
dynamic, it's going to create problems, especially given (1) and
the potential for DNS caches with operationally stale but
unexpired A records.
The IP address is static, so I dont have to worry about that I
would assume.
3. Putting any machine engaging in any
form of SMTP behind a device that performs malicious attacks on
basic SMTP functionality (such as Cisco's PIX/ASA assault on
SMTP that they ridiculously refer to as "fixup") is always a bad
idea.
This is behind a Cisco ASA. Hmmm.. I definitely have the inspect
statement there. You saying i should remove the ESMTP line?
policy-map global_policy
class inspection_default
inspect dns preset_dns_map
inspect ftp
inspect h323 h225
inspect h323 ras
inspect ip-options
inspect netbios
inspect rsh
inspect rtsp
inspect skinny
inspect esmtp
inspect sqlnet
inspect sunrpc
inspect tftp
inspect sip
inspect xdmcp
inspect pptp
4. If you run a mail server using a public
IP whose PTR resolves to a name in a domain that you don't
control and is obviously constructed from the IP address you
will have chronic delivery problems, some of them silent.
From what I can see, the PTR record points directly at my outside
IP address, on the domain I do control. Im pretty sure that is
correct but then again Im not sure of much when it comes to dns
stuff :)
Thank you again for your response, I really appreciate it.
Bob
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