You have decided to run a report on traffic under the Templates > Mailbox Traffic menu such as General Mailbox Traffic, Mailbox Traffic Across Time Interval or Mailbox by Traffic Level. Those reports include the "Count messages sent to n recipients" option in their Options tab, but also different detail levels in their Content tab.
The resulting report may show different figures for sent/received messages depending on how "Count messages sent to n recipients" is configured in the Options tab. But the fact that you also configured the report to display address types or the detail of correspondents is a key factor for counting messages.
Let us take an example: 1 message is sent to 4 correspondents.
- The first two belong to your organization.
- The third one is an external (Internet) correspondent.
- And the fourth is another Internet correspondent from a different SMTP domain.
1 Message count:
- If no check box is selected in the Detail level section of the Content tab, this message sent to multiple correspondents will be counted once.
- If the Correspondents' address type check box is selected, 1 message will be counted for each address type, regardless of the number of recipients. So it will be counted twice (once as internal, once as Internet).
- If the Correspondents' domains check box is selected, the number of messages will be 3: 1 for your Exchange organization, and 1 for each SMTP domain.
- If the Correspondents check box is now selected, the number of messages will be 4 even if the internal users belong to the same admin group.
n Messages count:
When n Messages is selected under the Options tab, ALL messages are counted. In other words, if we refer to the above example, the total of messages will always be 4. In this case, the number of sent messages should be similar or close to the number of received messages.
See also: FAQ, Why can I obtain different results in the General Mailbox Traffic report?