[Dovecot] From Maildir back to smtp

[Marc Perkel]

Not sure how this can be done.

Right now I'm running a free backup MX record service. People point 
their high MX records to my servers and if they go down we store the 
email. When they come back up it's delivered.

What I want to do is have a premium service that would allow them to 
view through IMAP the stored email. In order to do that I would have to 
deliver the email locally to a dovecot server - to a single account 
perhaps - and they can view/forward/delete etc.

But - when their server comes back online I'd like to gather up all the 
delivered email stored in Maildir format and run it back into smtp for 
delivery.

Has anyone even done something like this? Or is there an easier way that 
I'm missing?

Thanks in advance