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Does Exchange 2003 Distribution List with External Contacts sometime create uncontrolled email ?

Posted on 2007-11-16
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Last Modified: 2009-10-22
I created an Exchange 2003 Distribution list then added contacts with external email as members so the internal email users can email to a group of outside email addresses.
After a few days the external email addresses in this distribution group are getting email addressed to internal email accounts. (Internal email was routed by mistake)
The external email users are forwarded to internal users asking is'nt  this yours.
This was confidential internal company email not even addressed to them but someone inside the company. After I disabled the distribution group the problem stopped. An engineer said the same thing happened to him last year and he had to delete the all distribution groups for external email users. What is the right way to setup a distribution group in AD for sending email to a group of external email addresses and not have to worry about uncontrolled email, does anyone have a simulare experience ?

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Question by:cap7
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by:Sembee
ID: 20302099
That is not the standard behaviour. Email would only go to that group if someone sent it to the group, either on purpose or by setting their system to forward email to the group. You need to get hold of the headers of the message that was sent to an external user to see how it was routed and what addresses it was sent to.
Do NOT take the users word that they didn't make a mistake - users lie.

Simon.
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by:cap7
ID: 20302175
No I saw the emails it was evident that this is a real issue. I found one google search result about distribution groups doing this and somthing has to be be done to the AD receipant policy to prevent the receipant smtp email list form being corrupt; but is was just a paragraph on a tech forum page that is used for advertisements and does not go anywhere. I really know this is real and I can't find a solution. I may have to call microsoft.
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by:chumplet
ID: 20302294
I have not seen the issue that you're reporting, but we also have external users as part of internal distribution lists.  We've created an OU called "external contacts" where we create a new CONTACT (not user) for each external email address that we need to send to.  Then we create a new distribution list and add those contacts to that list.  Also, I typically "hide the addresses from the Global Address List" to help keep things clean, but your mileage may vary.

Does this fall in line with what you're doing?  We've not seen any *abuse* of these lists, or out-of-control email to them.

Chumplet
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by:chumplet
ID: 20302298
Famous quotes from Sembee... :)

"Do NOT take the users word that they didn't make a mistake - users lie."

I love it!
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by:Sembee
ID: 20302568
Contacts do get email addresses in your domain. Therefore if you have using dynamic distribution lists which are not carefully planned then it is possible for an external contact to get on to an internal address.

Simon.
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by:chumplet
ID: 20302631
Sembee is right about that.  You need to create the contact, add their external SMTP address, wait for the "email address propagation", and then delete any internal email addresses assigned to that contact.
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by:cap7
ID: 20302640
Yes, I know it possible for an external contact get on to an internal address  I Did not put the DL in a seperate OU yet. Does the DL have to be Univeral or Gobal ? What is wrong with using either one ?
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by:cap7
ID: 20302648
add their external SMTP address, wait for the "email address propagation",


How do you any internal email addresses assigned to that contact..where at?
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Sembee earned 500 total points
ID: 20302677
Internal email addresses will be set automatically. All mail enabled objects will get an email address on your domain - even external contacts. This can actually be useful as it means that external people can have an email address on your domain - but it can appear like spoofing.

Simon.
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Author Comment

by:cap7
ID: 20302730
How do you remove any internal email addresses assigned to that contact..where at?
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by:cap7
ID: 20305020
Can someone tell me the correct way to setup a Distribution group with contacts for external emails?
Does it need to be global or universal?
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Expert Comment

by:chumplet
ID: 20305127
Make the contacts, add a new SMTP address (during the creation process) with their external address.  After a few minutes *typically* your internal domain addresses will also propagate to those contacts.  On the "email addresses" tab, click on each of those addresses and remove them.  Do this for each contact that you need to create.

For the distribution list, simply create the list (default is fine; "global", I believe) and then add each of the contacts to that list.  Send an email to the dist list email address and verify that each of the contacts receives the test message.

Does that help?
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Author Comment

by:cap7
ID: 20309607
I get an error message when I try to remove the contact smtp internet email address ;
"This is the home email address of the recipient. I cannot be removed."
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by:chumplet
ID: 20309894
You'll need to set the "external" email address (whatever@msn.com, etc.) as the primary email address, then remove the others that have propagated down from your domain.
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by:Sembee
ID: 20319131
Thing is, I am pretty sure if you remove the internal address of the contact that the contact will not work correctly with Exchange. All Exchange objects need and email address in the default domain.

Simon.
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by:chumplet
ID: 20320938
I can guarantee that NONE of our internal "contacts" have default domain email addresses assigned to them.....and they still work for sending email to their address (whoever@msn.com, joesmith@gmail.com, etc.).
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Expert Comment

by:itsigny
ID: 20900282
Sorry but none of the instructions provided work. External contact included in Distribution list generates NDR when you sned to this distribution list from the internet because it is seen as relay by default by Exchange.
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