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Members of both Mail enabled Security Group (Univesal) and DL will not get duplicate emails----Is this correct? RRS feed

  • Question

  • Dear Experts,

    Exchange 2007 SP1 running in our organisation!

    I have

    1. Universal security group

    2.Universal Distribution group

    If "user-A" is member of both the above group, he will get a single email in his mailbox.....! is this normal?

    I have

    1. DL1

    2. DL2

    If user-B is member of both the group, he will get single email to his mailbox.......is This also  normal?

     

    Please let me know the following queries????

    1. When I will get duplicate emails (If member is in both Groups\DL). Is duplicate emails are really generated?

    2. I want to make sure this as our hiher authority DL\groups will have cross membership (Entries in different groups) so they should not get emails twice or thrice if tehy are member of multiple groups

     

    Please clarify my doubts

    Manju

    Thursday, January 12, 2012 7:48 AM

Answers

  • Exchange had a built in mechanism for checking duplicate emails to mailboxes.  Therefore if a user is in two mail enabled groups, Exchange will make sure one copy goes to the mailbox.  For more information on the settings for Exchange 2007 and Duplicate Message Detection, see this link:

    http://technet.microsoft.com/en-us/library/dd577073(EXCHG.80).aspx


    JAUCG
    Thursday, January 12, 2012 1:47 PM
  • On Thu, 12 Jan 2012 13:47:20 +0000, JAUCG wrote:
     
    >Exchange had a built in mechanism for checking duplicate emails to mailboxes. Therefore if a user is in two mail enabled groups, Exchange will make sure one copy goes to the mailbox.
     
    That's mostly true. However, the possibility exists that each DL is
    expanded on a different HT server. In that case the message-id will be
    different to the one send by the other HT server. So the possibility
    exists that people may still receive multiples of the "same" message.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Friday, January 13, 2012 2:57 AM
  • On Tue, 17 Jan 2012 07:54:47 +0000, manjurainbow123 wrote:
     
    >Dear Rich Matheisen and JAUCG,
    >
    >Thanks a lot for the explanation.
    >
    >Q) What if it is a multiple domain environment? Ex: Single forest and we have 3 SMTP domains?
     
    The number of domains won't have any effect on the expansion of the
    DL. The DL membership is in the Global Catalog.
     
    The number of HT servers you have, and the number of AD sites is much
    more important. But unless you have expansion servers assigned to your
    DLs this usually doesn't present a problem, either.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Wednesday, January 18, 2012 1:10 AM

All replies

  • Exchange had a built in mechanism for checking duplicate emails to mailboxes.  Therefore if a user is in two mail enabled groups, Exchange will make sure one copy goes to the mailbox.  For more information on the settings for Exchange 2007 and Duplicate Message Detection, see this link:

    http://technet.microsoft.com/en-us/library/dd577073(EXCHG.80).aspx


    JAUCG
    Thursday, January 12, 2012 1:47 PM
  • On Thu, 12 Jan 2012 13:47:20 +0000, JAUCG wrote:
     
    >Exchange had a built in mechanism for checking duplicate emails to mailboxes. Therefore if a user is in two mail enabled groups, Exchange will make sure one copy goes to the mailbox.
     
    That's mostly true. However, the possibility exists that each DL is
    expanded on a different HT server. In that case the message-id will be
    different to the one send by the other HT server. So the possibility
    exists that people may still receive multiples of the "same" message.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Friday, January 13, 2012 2:57 AM
  • Understood, but that would take a special setting on the Distribution Group (hard coding a different expansion server).  I believe that unless that is set, one Hub server will serve as the expansion server for both DLs for the same message and avoid the mess of duplicate messages.  Which is the scenario he is referring to.  There are other parameters for the Hub role that could also cause duplicates, but again, in most normal situations, duplicates are avoided.


    JAUCG
    Friday, January 13, 2012 4:00 AM
  • On Fri, 13 Jan 2012 04:00:34 +0000, JAUCG wrote:
     
    >Understood, but that would take a special setting on the Distribution Group (hard coding a different expansion server).
     
    That's correct. I just wanted to point out that there's a possibility
    that multiples of the same message could still be received.
     
    >I believe that unless that is set, one Hub server will serve as the expansion server for both DLs for the same message and avoid the mess of duplicate messages. Which is the scenario he is referring to. There are other parameters for the Hub role that could also cause duplicates, but again, in most normal situations, duplicates are avoided.
     
    Always expect the unexpected. :-)
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Friday, January 13, 2012 5:08 AM
  • Dear Rich Matheisen and JAUCG,

    Thanks a lot for the explanation.

    Q) What if it is a multiple domain environment? Ex: Single forest and we have 3 SMTP domains?

     

    Manju

    Tuesday, January 17, 2012 7:54 AM
  • Manju, the above URL is good explanatory. Typically, a duplicate message occurs if the distribution list is expanded on a server other than the Exchange server from which the message was sent or if it is a hidden distribution list.
    Tuesday, January 17, 2012 9:18 AM
  • On Tue, 17 Jan 2012 07:54:47 +0000, manjurainbow123 wrote:
     
    >Dear Rich Matheisen and JAUCG,
    >
    >Thanks a lot for the explanation.
    >
    >Q) What if it is a multiple domain environment? Ex: Single forest and we have 3 SMTP domains?
     
    The number of domains won't have any effect on the expansion of the
    DL. The DL membership is in the Global Catalog.
     
    The number of HT servers you have, and the number of AD sites is much
    more important. But unless you have expansion servers assigned to your
    DLs this usually doesn't present a problem, either.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Wednesday, January 18, 2012 1:10 AM
  • Cool Rich Matheisen

    Manju

    Wednesday, January 18, 2012 10:20 AM