I reported it in a different thread. Will report it here with a sample code which can reproduce the issue. 1. 1000 emails, each has 3000 addresses 2. The total size of 1000 emails is 50MB 3. The size of PST is: 1.08GB, 2…...investigation and performance comparison. curtisyamada June 28, 2017...performance by the following comparison code and update your code...