Yes Please, we need this basic function !
When will it be implemented ?
Thanks

Please do add this function from loosing users asap. Syncing flags is just a fundamental feature for every single email apps. There are a huge group of users who are used to flagging emails instead of moving them to an additional "starred" folder. I would suggest that DO NOT FORCE USERS TO ACCEPT YOUR RULES. It also happens that Airmail would automatically generate an "archive" folder while I never use the "archive" feature. I even couldn't delete it. In fact, Airmail can introduce another way to improve the efficiency by making a function optional. If I leave Airmail for iPhone, this would be the only reason.

This should have been implemented when the iOS app launched. Very disappointed that it hasn't yet. The mobile and desktop apps feel like two different entities because of this. I read an email on my Mac, but the notification and badge count is still present on my phone.

I especially like how I can 'pin' emails in Spark to remain near the top of it's smart mailbox, and have 'pinned' mapped to the Starred mailbox/label with my Google Apps email.

Yes, and not just the actual "flag" status, but the indication of a message that has been replied to, forwarded, etc. Example... if I receive an email on my Mac and reply to it on my Mac, Airmail on iOS does not show that it has been replied to.

Yes! Please!