Thank you for using Aspose.Email.
Aspose.Email feature of working with PSTs is based on mail protocols, and as mail protocols are not intended for exchanging messages with such a large size, that is why you are facing some issues while adding msg files to PST. Regarding huge amounts of data to PST, we haven’t tested the component at least with terabytes of data, but we have performed various tests that included emails contributing to a size of 5-6 GB of data, and never faced any slow affect during our operations.
Could you please tell us if you are using the dll in multithreaded programming for PST operations? Please refer to the thread safety instuctions for PST class in this regard which states that “Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.”. If you could provide us some sample application that we can use to reproduce this issue at our end, we’ll look into it and assist you further.