I have some experience with the 28it Exchange Connector, but my clients didn't want to change. At the moment they are using Chilkat and the SMTP server of the Exchange Server. The BCC's are sent to a specific folder. This works fine, but if I could start from scratch I definitely would use the Exchange Connector. Setting up the SMTP server with Exchange, that we were allowed to use, wasn't an easy task. If you can avoid this I would do it. The Exchange Connector worked in a testing environment with a on premise and on a Office 365 Exchange Server.