Firstly, as others have stated, your pricing is way too complicated for anyone to understand and figure out how much they would be charged. It would be better to make some assumptions and go with pricing based on account, aliases, storage, etc. Your current pricing is almost like one of those cloud service pricing calculators. Very nice in theory for paying based on usage, but practically next to impossible to make any sort of cost estimates on.
Secondly, your privacy policy is very short and doesn't give a lot of comfort. Take a look at Posteo.de to see how privacy is handled. It's one of the best that I know of.
On pricing, also compare with mailbox.org.