This isn't http, there is no redirect command. Also the two protocols
are completely different and non-compatable.
The normal option for this is to just require encryption, then if they
use normal IMAP and attempt to do anything except secure it using TLS,
the connection gets dropped.
Quoting Frank Bonnet <f.bonnet at esiee.fr>:
> Hello
>
> Is it possible to configure Dovecot (2) to "redirect" IMAP
> connexions to IMAPS ?
>
> I know it would be possible with ipfw on the server but I wonder
> if dovecot has such capability.
>
> thanks