We are upgrading from PHPList 2.10.15 to 3.2.4. In 2.10.15 we are able to have 5 campaigns running at the same time to the same lists of email addresses. Also, PHPList knew not to send more than one message per minute to the same domain. We had to start the campaigns at different times, we have them scheduled (embargoed) an hour apart. If we had two ready to be sent at the same time, say it was 10:00 and we had one embargoed for 9:00 (that we forgot to process) and one for 10:00 and we clicked process queue, the system would do as duncanc states above, it would literally split the list of emails between the two campaigns and eventually the campaigns would show negative numbers in the sent column. So, we were very careful that we never had more than one queued up to start at the same time. As long as they were processed at different times, we could have 5 campaigns running at the same time to the same full lists of recipients, the same email addresses were not receiving the 5 campaigns at the same time, but eventually throughout the day each email address on the list would receive the 5 campaigns. It sounds like you are saying PHPList is no longer capable of doing this. What would be the use in having the list split up between the campaigns so each campaign is only sent to part of the list?