I want to install an imap-mailserver for a small internal net (up to 25 users) on an debian etch system and want to use it also to receice mails from various external e-mailaddresses.
I found this http://workaround.org/articles/ispmail-etch/index.html.de instruction which sounds realy good.

I also understand that i can use fetchmail to get mails from various external accounts on my mailserver by telling fetchmail that
and that i can use a smarthost by using /etc/postfix/sasl_password and writing something like

mail.externaldomain.net usernam@externaldomain.netassword

into this file. But as far as I understand this means, that all mail to external recipients is sent with the account usernam@externaldomain.net in the "From:" field.

What i want to know is. Is there a way to use postfix like a "reverse"fetchmail by telling it somehow, that it should use different smathosts with different accounts and different passwords for different localaccounts?

I mean is there a way to define something like:
so that all mails to external recipients are stored in the sentdirectory of my intern mailserver and sent via different smarthosts with different "from:" fields to the external recipients and all answers where fetched with fetchmail from the different external email-accounts and stored in my intern mailserver and there available to the specified internal users and all my internal mails are only stored and distibuted internal?

Why are you using a smarthost entry to send outbound e-mails any way? Have you tried just letting Postfix handle the delivery by doing DNS lookups?

Sorry i forgot to tell. I'm using a DSL-connection with a dynamic IP-Address and since most providers dont accept smtp-connections from dynamic IP's and since I also dont want my domain to be an external known domain and only want to use it internal, as far as I understood, this could only be possible by use of a smarthost.