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Transport rule for recipient count

    Question

  • I am looking for a way using a transport rule or otherwise against e-mails with high recipient counts. It is to prevent future instances of bulk e-mails being sent with the addresses in the To: instead of BCC:. Ideally if it can be used with the 'forward the message to addresses for moderation' as a safety net.
    Friday, September 26, 2014 9:57 AM

Answers

  • You can't block inbound messages with a transport rule according to the number of recipients on the To: line.  You would need to either write your own transport add-on or have a separate appliance for handling this in order to accomplish your goal.
    • Marked as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Unmarked as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 12:06 PM
  • Why don't you set the max recipient limit at global level and who really wants to send bulk mail give them higher limit at mailbox level for exception (for example, bulk communication from an HR mailbox)

    Restrict the Number of Recipients per Message - http://technet.microsoft.com/en-us/library/bb310760(v=exchg.141).aspx

    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 1:55 PM
  • Actually, the org limit for recipients trumps the individual limit.  If the individual limit is lower, it works, but if it is higher, the org limit kicks in.  If you need to send mass mailings internally, you use distribution groups - they only count as a single recipient. Just make sure your huge groups are both moderated, and not available to external senders.
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 3:19 PM
  • Right, set higher limit at org level, lower level at individual level and set exception again at individual level by increasing... and Agree about distribution list... Here is good understanding on this... http://blogs.technet.com/b/mr_proactive/archive/2011/08/25/maximum-recipients-per-message-and-exceptions.aspx
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 5:17 PM

All replies

  • You can't block inbound messages with a transport rule according to the number of recipients on the To: line.  You would need to either write your own transport add-on or have a separate appliance for handling this in order to accomplish your goal.
    • Marked as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Unmarked as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 12:06 PM
  • It was for outbound. Would this be the same?
    Friday, September 26, 2014 1:14 PM
  • Why don't you set the max recipient limit at global level and who really wants to send bulk mail give them higher limit at mailbox level for exception (for example, bulk communication from an HR mailbox)

    Restrict the Number of Recipients per Message - http://technet.microsoft.com/en-us/library/bb310760(v=exchg.141).aspx

    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 1:55 PM
  • That could work. I will look into the viability.

    Friday, September 26, 2014 2:33 PM
  • Actually, the org limit for recipients trumps the individual limit.  If the individual limit is lower, it works, but if it is higher, the org limit kicks in.  If you need to send mass mailings internally, you use distribution groups - they only count as a single recipient. Just make sure your huge groups are both moderated, and not available to external senders.
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 3:19 PM
  • Right, set higher limit at org level, lower level at individual level and set exception again at individual level by increasing... and Agree about distribution list... Here is good understanding on this... http://blogs.technet.com/b/mr_proactive/archive/2011/08/25/maximum-recipients-per-message-and-exceptions.aspx
    • Proposed as answer by Belinda Ma Monday, September 29, 2014 7:27 AM
    • Marked as answer by Belinda Ma Monday, October 6, 2014 1:57 AM
    Friday, September 26, 2014 5:17 PM
  • why can't be a transport rule created with a regex detecting number of recipients? Since all addresses are separated by comma, seems like an easy thing to do.
    Wednesday, October 14, 2015 4:56 PM
  • How do you handle addresses where there's a comma in the address - not in the SMTP address, but in the display part, such as "Thompson, John [jthompson@e-mailaddress.com]"?  And that's just a simple example - there are other ways to include any separators that will mess up just about any RegEx ...

    Will Martin ...
    -join ('77696c6c406d617274696e2d66616d696c6965732e6f7267' -split '(?<=\G.{2})' | ? { $_ } | % { [char][int]"0x$_" })

    Wednesday, October 14, 2015 5:46 PM