5.7.1 smtp;550 5.7.1 Email errors sending through SBS2003 Exchange

Our office recently moved to a new location thus having to get a new static IP address. Everything was working fine prior to the move.
1. We our mx records pointing to mail.companyname.com
2. The name record mail.companyname.com has been pointed to our new IP address.
3. All networking hardware remained the same it was just moved from one building to another.

but we are getting random emails that fail to send with the following error code:
You do not have permission to send to this recipient. For assistance, contact your system administrator.
  <mail.companyname.com #5.7.1 smtp;550 5.7.1 <hdk_tx@xxxxxxxxx.net>... Refused - Please relay through your ISP mail server HOST static-11-111-111-1.xxxx.fios.verizon.net>

Any assistance is appreciated.
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Kerem ERSOYConnect With a Mentor PresidentCommented:
The problem is they are getting a reverse DNS lookup for your domain and getting a hostname of static-11-111-111-1.xxxx.fios.verizon.net . In this case they are rejecting the mail from you. It is reflected in the message you get: "Please relay through mail host.

To correct this:
- Ask verizone (I guess your ISP) to enter your correct SMTP hostname mail.companyname.me in the reverse lookup zones for your. You can verify this with using nslookup and your ipname. Such as:

nslookup ( being the IP address of mail.companyname.com) when the query gives you that mail.companyname.com you'll stop getting such messages.

- Furthermore if you add an SPF record to your DNS zone it will improve the situation about 5.7.1. errors.
Kerem ERSOYPresidentCommented:
- Another solution would be to use Verizon.net SMTP server to relay your mail. So that verizon SMTP servers will deliver your mail on your behalf. But in this case you should definitely implement SPF and indicate that virezone.net SMTP servers are autorized to deliver your mail. I am not sure if Verizon charges extra for this service.

For further info on SPF and automatic SPF record generator::


I hope this helps.

localcircuitAuthor Commented:
I am guessing you can just call Verizon Technical Support up and have them add the SMTP record? I did a search and found nothing on their website about it.

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You need to ask the ISP to set a reverse DNS aka PTR record. I doubt if it is on the web site, but call them and ask. If they tell you to speak to your domain name registrar, ask to speak to someone who understands how the internet works.

SPF records are not going to fix this problem.

localcircuitAuthor Commented:
Thanks, I will be making this call today. Just got back into town.
Kerem ERSOYPresidentCommented:

> SPF records are not going to fix this problem.

It was the part of the solution I'd suggested either to correct the reverse DNS record or relay mail through verizon. But if they prefer to send through verizon then some receivers would reject their mail since the sender and the relayer are different domains. SPF was suggested to fix this, as a measure to help the remote receiver verify if verizon is a legitimate relayer for the domain. Please read the entire suggestion before speculating.
I stand by my point of SPF records not resolving this problem.

No site should be doing hard failures on SPF records due to their poor implementation rate.

Anyone who does reject email because the email is coming from a different host name to the email address is a fool, because I would estimate a very high percentage of email comes out of a different host name.
I know of one server that hosts well in excess of 100,000 domains. All email comes out of a generic domain.

There is this belief that SPF records will resolve everything with email delivery. In actual fact they will not - I would actually go as far as to say SPF records will not make any difference.
The number of sites actively using them is very low, and those that do use them for scoring only because anything else is foolish and will result in legitimate email being dropped. It would take a major ISP such as AOL to announce that they would refuse to accept email from any domain without SPF records to get the use to a level where they can be relied upon. Chicken and egg unfortunately.

Kerem ERSOYPresidentCommented:
> No site should be doing hard failures on SPF records due to their poor implementation rate.

Hotmail and GMAIL ueses SPF heavily. Even Microsoft just introduced a site which produces SPF records automatically. You might not prefer to send SPF or prfer to ignore these sites but SPF is already a hot topic for companies with large e-mail auridences

> There is this belief that SPF records will resolve everything with email delivery. In actual fact they will > not - I would actually go as far as to say SPF records will not make any difference.

Nobody believes that but since more and more bigger email service providers accept the use of it people need to be ready. Furthermore it is just two lines. Unfortunately our beliefs don't count. For a glitchles operation we need the follow requirements. If nobody obys the standards even Internet can't stay what it is. Don't forget internet is also large set of standards that people follow closely.
Kerem ERSOYPresidentCommented:
Anyway I had suggested the SPF as a very legitimate part of suggestion and I still hold it. Please don't get stuck to this little detail. If they want to use another Provider to relay their mail they'll ultimately hit a site which will reject thier mail. If they are rather pragmatic they'd better use SPF too as a preventive measure.
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