Auth by ip address

[Marc]

>  Hi
>  is possible authentication by ip address in dovecot?
>   What i need.
>  Now auth is by PAM (Active directory), i want application password (its plugin
> to Roundcube, passwords in mysql) for  example android email client.
>  I know that Multiple Authentication Databases work but i want when user auth
> from public network use sql and when from internal network use both sql and
> then pam.
> 

I recently I asked something similar (allow authentication without password for a specific user name), and am looking to resolve this via pam modules. I think the solution to your issue is going to be quite similar.
However, I am not sure what you are trying to do, and if what you are looking for is even good. If you want to use roundecube. Why not just enable user imap authentication?
I would say you really need to know what you are doing, when you start looking at no authentication.