better delivery mechanism to maildir?

As many of you probably are, I'm using Postfix together with Dovecot. Postfix delivers mail for my users by writing them directly to the filesystem (maildir).

I wonder is there a better alternative? I'd like to separate the two services on different physical machines, so a shared filesystem isn't trivial any more. (I'd also like to stay with maildir storage and rather not do SQL or similar.)

Can mail be delivered via IMAP for example? Or is there some other delivery protocol I don't know about that both Dovecot and Postfix support?

Thanks!