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#5.5.0 smtp;521-EHLO/HELO error when sending emails to Comcast.net or aol.com

Posted on 2006-06-29
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Last Modified: 2010-03-06


Background info:  we have one server which has Windows Server 2003 SB...we are using Exchange internally only (for shared calendar, contacts). Our ISP is still hosting our email and I have set each user up in Outlook with their Exchange account as well as their POP3 email account.

So, in brief, the emails are coming and going thru the pop account, but are being stored in an exchange account (for backup reasons, and because some users roam to different computers).

Does anyone know why emails sent aol.com or comcast.net keep on kicking back the following email?:
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <???.????.local #5.5.0 smtp;521-ECHO/HELO from sender ???????? does not map to ????.????.local in DNS>

I have read other posts, but I'm not sure they apply to me since we are not functionally using Exchange to send or receive emails.

Thanks,  Dave
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Question by:bswensen
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by:Sembee
ID: 17014079
Your server's SMTP banner says that it is servername.domain.local
You need to correct that.

ESM, Servers, <your server>, Protocols, SMTP. Right click on the default SMTP VS and choose Properties. Click on the tab Delivery and then Advanced. Change the entry in the FQDN to what the server is known as on the internet.
If the server doesn't have a DNS entry on the internet, then configure an SMTP Connector to route email through your ISP. http://www.amset.info/exchange/smtp-connector.asp

Your emails may be coming in through the POP3 connection, but I would be surprised if they were going out through it.
Once you introduce an Exchange configuration to Outlook, it will try and use it for all email. If you are sending email to a mix of internal and external users then Outlook will send all email through Exchange.

Exchange is an email server - if you are on any kind of permanent internet connection then you will get a much better user experience using Exchange for what it is designed for.
Even if you aren't using Exchange for email, you should still configure it as if it is, as email will very often slip out through Exchange.

Simon.
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Expert Comment

by:Exchgen
ID: 17014416
Aol sees the sender IP and rejects it if does not get a reverse pointer back.

Ensure that Email does not leave through exchange, do the needful as simon has suggested, rename the FQDN to match the sender IP and not the MX record.

Raghu
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Author Comment

by:bswensen
ID: 17015281
Simon...my FQDN is servername.domain.local...as you said it would be.

You say change this to what the server is known as on the internet. Is this the FQDN of our email hostname...which is mail.domain.com?

Thanks, Dave
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Accepted Solution

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Sembee earned 250 total points
ID: 17016763
You will have an external IP address - every machine that is on the internet does. This could be a dedicated or a shared IP address.
Either way, it needs to have a host name attached to it. That could be mail.domain.com - it may not. If you are getting your email from an ISP then it may not be mail.domain.com
If you don't have a host name, then ask whoever looks after your domain name (this may be your ISP, or it could be a domain name registrar) to create one for you, pointing at your external IP address. You could use office.domain.com, owa.domain.com etc.
Once you have that host created, enter that information in to the FQDN box.

Simon.
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