Warning - Reverse DNS does not match SMTP Banner

Discussion regarding the Standard version.
abacabb
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Joined: Wed Mar 10, 2010 2:26 pm

Warning - Reverse DNS does not match SMTP Banner

Post by abacabb » Thu Apr 01, 2010 7:27 pm

My original issue is that Hotmail keeps putting my mail into the junk folder. I went on mxtoolbox.com and ran an SMTP test. Everything checked out fine except for this one warning:

Warning - Reverse DNS does not match SMTP Banner


How can I make the RDNS match my SMTP Banner? Is this an ISP thing or is there something i can do on my mail enable side?

I am hosting my own DNS as well using DNS in Windows Server 2003.

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Fri Apr 02, 2010 8:09 am

It's "an ISP thing..." You can change your SMTP greeting to match the your reverse DNS for your ISP assigned IP, but then your IP may change if you are on a dynamic IP plan...
Microsoft MVP (2004 through 2008)

abacabb
Posts: 8
Joined: Wed Mar 10, 2010 2:26 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by abacabb » Fri Apr 02, 2010 4:15 pm

I was able to change it within mail enable, but hotmail still filters my mail to the junk folder.
Initially when I did a DNS report on dnsstuff.com, it gave me a few name server errors. I have since parked my nameservers at godaddy which took care of all of the errors I had. But hotmail still filters my mail to junk. I did a blacklist check and I am not on any of them.

I also ran all of the tests on mxtoolbox.com and all of them checked out fine.

any ideas?

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Fri Apr 02, 2010 6:02 pm

Are you on a dynamic IP plan with your ISP? If so, then you may either need to relay all your outbound through their email servers or modify your plan for a correctly assigned/identified static assignment. There is a growing number of servers that will not accept email correctly from dynamic IPs.
Microsoft MVP (2004 through 2008)

abacabb
Posts: 8
Joined: Wed Mar 10, 2010 2:26 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by abacabb » Fri Apr 02, 2010 6:29 pm

My IP is static

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Fri Apr 02, 2010 6:33 pm

Then you need to work with your ISP to ensure that it is correctly identified as such. There are instances in which the ISP or the various black lists have IP assignments incorrectly identified.
Microsoft MVP (2004 through 2008)

Steevo
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Joined: Fri Jul 15, 2005 4:45 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by Steevo » Sat Apr 03, 2010 3:32 pm

That particular warning,
Warning - Reverse DNS does not match SMTP Banner
is not a valid method of filtering spam. I can't believe Hotmail does that.

There are millions of mailservers that send and receive mail for multiple domains, and the SMTP Banner is gonna be what it is.
I set my SMTP banner to one of my domains, you gotta pick just one. But that doesn't stop you from setting up more domains on that machine.

What are you supposed to do if you host 40 domains? 400,000 domains? There's plenty of mailservers like that!
You just *can't* set the SMTP welcome banner at more than one, when an inbound connection occurs you *can't* know which of your hosted mail domains it's for.

What evidence do you have that Hotmail is using that parameter for filtering?

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Sat Apr 03, 2010 7:33 pm

"is not a valid method of filtering spam"

You have every right to your opinion, but it is used quite frequently by government systems. The simple solution is to smarthost through a properly configured relay (e.g. your ISP's relays).
Microsoft MVP (2004 through 2008)

Steevo
Posts: 50
Joined: Fri Jul 15, 2005 4:45 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by Steevo » Sat Apr 03, 2010 9:45 pm

cszeto wrote:"is not a valid method of filtering spam"

You have every right to your opinion, but it is used quite frequently by government systems. The simple solution is to smarthost through a properly configured relay (e.g. your ISP's relays).
I am doing that, because even though I have had the very same static IP since 1999, I cannot get ATT to change the rDNS. So I smarthost. It solved a few problems with people using, well, invalid methods of filtering spam. Heh.

I can't imagine hotmail would reject mail based on the rDNS not matching the SMTP name. That would result in many false positives.
I have asked them if they do. Hopefully my contact there will respond.

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Sat Apr 03, 2010 11:33 pm

Most ISPs will update their rDNS for their business account IPs. The other possible solution may be to host your own DNS, but then that would typically require at least two DNS servers.

A simple test for Hotmail is to just send an email from just that configuration to gauge the results.
Microsoft MVP (2004 through 2008)

Steevo
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Joined: Fri Jul 15, 2005 4:45 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by Steevo » Sun Apr 04, 2010 12:02 am

cszeto wrote:Most ISPs will update their rDNS for their business account IPs. The other possible solution may be to host your own DNS, but then that would typically require at least two DNS servers.
For a T1 line, of course, you order the rDNS you need. But if you host mail for a number of domains don't you have the same problem?

Why would running your own DNS server solve anything, though?

Lots of small companies run their own mail server on a fixed IP DSL line. I have two I am responsible for, one is actually static since 1999, the other is PPPOE that ATT calls sticky static for about $100 a month. We have 5 IPs. I wouldn't have any idea how to get them to change the rDNS on either of them.

Most of the time when you call ATT you get some guy named "Fred" who has an Indian accent and can only help you with the PPPOE problems on your residential adsl line.

If you don't use PPPOE, like on my circuit I've had static since 1999, well, they can't help. In fact it absolutely blows their minds!

Fortunately when you finally get to the local ATT guys in America it's no problem. But that sure takes time.

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Sun Apr 04, 2010 12:11 am

If it is a business account, then get a hold of your business account manager for assistance. Chances are, there is an automated self-service portal that just needs to be communicated.

Actually, on second thought or thinking it through more throughly, hosting your own DNS will not resolved rDNS situation. That needs to be addressed by the IP block owner/administrator - the ISP in most cases.
Microsoft MVP (2004 through 2008)

Steevo
Posts: 50
Joined: Fri Jul 15, 2005 4:45 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by Steevo » Sun Apr 04, 2010 1:52 am

cszeto wrote:If it is a business account, then get a hold of your business account manager for assistance. Chances are, there is an automated self-service portal that just needs to be communicated.
I suspect if I could find anyone like that at ATT I would find they would be *more* than happy to set me up with all that on a T1 for $600 a month. On a DSL line, even a static DSL line, probably not.
cszeto wrote:Actually, on second thought or thinking it through more throughly, hosting your own DNS will not resolved rDNS situation. That needs to be addressed by the IP block owner/administrator - the ISP in most cases.
I didn't really think that would change anything. And if your mailserver hosts mail for a number of domains I don't see what setting the rDNS to anything specific would change either.

It would still be a problem for some people who use an invalid method of spam identification. The only way to ID spam is by either content, which is unreliable, or by volume, which can be reliable in the case of DCC. I have had single, personally typed emails typed by me, in response to an email, and that blocked as spam. People calling me

cszeto
Posts: 527
Joined: Sat Feb 07, 2004 8:06 am
Location: Arizona, USA

Re: Warning - Reverse DNS does not match SMTP Banner

Post by cszeto » Sun Apr 04, 2010 2:08 am

Your statements seem to be limited to finite experiences. This is not a negative dig, but just a comment that there is a bigger world out there...

Qwest who is not generally known to be the best ISP out there has a self-service portal for their business DSL service that allows/facilitate the setting of just that. Very good chance that AT&T business DSL has similar capabilities as AT&T business services tend to be the more full featured provider in most cases. Their residential services is an entirely different matter as it is really the former SBC stuff.

"invalid method of spam identification"

Problem here is that it is not actually utilized as a method of spam identification, but of identifying "trusted" hosts/connections. If someone like Hotmail choose to factor that in or specifically require that level of establishing "trust" then it is their users who need to step up any let them know that how they feel about it. Most ISPs have their relays setup "correctly" in this manner, so it may be viewed upon by them (Hotmail) as a "non-issue" (not to take either position of whether it is correct or not).
Microsoft MVP (2004 through 2008)

Steevo
Posts: 50
Joined: Fri Jul 15, 2005 4:45 pm

Re: Warning - Reverse DNS does not match SMTP Banner

Post by Steevo » Sun Apr 04, 2010 3:59 am

cszeto wrote:Your statements seem to be limited to finite experiences. This is not a negative dig, but just a comment that there is a bigger world out there...

Qwest who is not generally known to be the best ISP out there has a self-service portal for their business DSL service that allows/facilitate the setting of just that. Very good chance that AT&T business DSL has similar capabilities as AT&T business services tend to be the more full featured provider in most cases. Their residential services is an entirely different matter as it is really the former SBC stuff.
I admit I can't find crap on the ATT network. When it was Pacbell and then SBC there were easy to find system status pages, you could see outages and everything in realtime. We had an outage here last week. I reported it, the trace crapped out at a server near here, about 5 hops from me. The rep said there was no longer any publicly accessible system status page. Now it's all internal. It's a problem of a whole lot of diverse networks, ATT, SBC, Pacbell, Bellsouth all merged in somewhat a haphazard way by ATT. Kind of a mess.

For example, I go online to pay my ATT bill, I swear, if you start at ATT.com rather than a page I have bookmarked you *can't* get to their billpay site. Rather, I invariably end up at ATT wireless and they are trying to help me pay my ATT wireless bill. Sheesh. Thing is too big, fragmented. They may well have a page to set rDNS but you'd never find it. Well, maybe you'd find the one for Bellsouth, whose site was always organized logically. That didn't help me, however not being in Bellsouth land.
cszeto wrote:"invalid method of spam identification"

Problem here is that it is not actually utilized as a method of spam identification, but of identifying "trusted" hosts/connections. If someone like Hotmail choose to factor that in or specifically require that level of establishing "trust" then it is their users who need to step up any let them know that how they feel about it. Most ISPs have their relays setup "correctly" in this manner, so it may be viewed upon by them (Hotmail) as a "non-issue" (not to take either position of whether it is correct or not).
Heh. A mild distinction since the OP was complaining about Hotmail filtering his mail into folders on his webmail based on that invalid criteria. But it's not established that they are actually doing that. Only that the OP couldn't see any other reason.

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