The Programs Mailing Performance report provides information about the performance of emails that are sent by a specified Program. The mailings are divided by steps in the program and provide common mailing metrics.
When a regular email is sent in Acoustic Campaign, it records when the send completes and that is reflected in the Sent timestamp.
That doesn't necessarily mean that every contact was sent at exactly 11:04 AM. If the mailing was a 24-hour STO send, for example, some contacts might have been sent on April 6th at 10 PM. They would still be considered in the sent count for a mailing that shows as Sent at 11:04 AM on April 7th. It is the nature of "rolling up" reporting to show a simple timestamp to represent the time at which the mailing sent. If you exported the Sent CSV for the email, you would see that the Sent times for each contact can fluctuate (even into a different day).
In the same way, Program Mailings aren't so straightforward as the single timestamp that represents when the send occurred. This is because a Program Mailing can be Sending continuously, many times throughout the day. For the sake of simplicity, Acoustic Campaign rolls up the sending for a Program Mailing ID into a single Report ID for that day. So if a Program was continuously Sending out a particular Step Mailing during a day, a new Report ID is not created for each one; sending metrics are instead grouped.
For example, assume that a Program Mailing was Sending continuously between April 4th and 8th. In the Reporting data, the following is recorded:
|4/4/18 2:48:58 PM||369854333||10|
|4/5/18 4:08:53 PM||369856783||3|
|4/6/18 7:42:18 PM||369859873||17|
When you review the Program Mailing Performance Report and see the number that represents the count of how many contacts were sent in the time range that you specified, Acoustic Campaign refers to the grouped metrics like you see above. However, when you click on the Number Sent, the grouped metrics are not referenced. Instead, the raw data for the time range that you specified is viewed. The 10 that represents the number that is Sent for the Report ID that was recorded at 4/4/18 at 2:48:58 PM does not mean that all 10 contacts were sent at 2:48:58 PM on April 4th. Some of the contacts that might have been counted into the grouping could have been sent earlier in the day on April 5th. So when the Program Mailing Contacts Sent screen is loaded, the raw data for sent is referenced and the number of contacts that are loaded can fluctuate to a great degree from the number sent seen on the previous screen.
Also, the number sent on the Mailing Performance Report excludes suppressed contacts, whereas the Program Mailing Contacts Sent screen does not exclude suppressed contacts. This can contribute to the different numbers witnessed between the two pages.