Question: I want to know if i can sort the sent items folder by "Sent to" instead of "Sent By" which is obviously myself.. I find it strange that this is not a sort option.

Answer (by Liang Chen, one of our Messaging Dev Leads):

No you can't. With its current design the email list view is optimized with a set of specially handled properties (sender, subject, and time) for better performance and in Sent folder you need recipient instead of sender, which requires some expensive database operation and will slow down performance. This is an unfortunate tradeoff we had to make between performance of more important scenario (inbox folder) and user experience of less important scenario (Sent folder) under current restriction.