Email Clients: Please join us in the 21st Century

Sorry but I am just fed up. Mail.app, Outlook, Thunderbird, all of them are stuck in the past and the developers need to get their acts together before users collectively hunt them down for silly slapping.

Dear email client developers,
Your software runs on these machines called “computers.” Please write your software to use their functionality. Here are three improvements I offer at no charge which, as a programmer, seem not that difficult to implement. Do two and you’re my pal, do three and I will buy you dinner.
I should be able to designate a default account from which to send messages on a per contact or per domain basis; messages to co-workers should come from my work account, messages to mailing lists should come from the account subscribed to that list.
Spam is a huge headache. However if I mark a message as not spam I should be able to indicate the sender address should from then on be considered not spam, without adding the sender to my contact list.
In this era of multiple email accounts unified inboxes are great. But many people write rules to get messages sorted to other folders. So how about making it easy to see all unread messages in one place regardless of account and folder?
Feel free to follow up with questions or comments on Twitter.
Your ardent admirer,
Bill