I don't really care about storing past emails and I'm pretty sure that lots of others don't either because your competition doesn't seem to offer it in a lot of cases.
For those like myself, storage is just an unnecessary expense.
We will surely take that into account and carve it as an add-on. (Postmark did the same recently with their retention-add-on)
We are early in the product phase so feedback like yours is very valuable!
Thanks again
