eMail Relaying to ISP using SMPT-Auth login

[Michael Przysucha <mp@abi-2k3.net>]

I've got a problem with my eMail-client and my ISP, the client does not support the SMTP-Auth machanisms required by 
my ISP.
Trying to solve the problem I wanted to set up a Debian box (Soekris net4501 headless system) with a relaying system. I 
tried sendmail, postfix, exim4 and so on but it didn't work any way. the system should work the way described in the 
graphic below, maybe someone can help selecting the right program an configuring it for this purpose!?

Thanks in advance,
Michael Przysucha


eMail-client (Opera 5.12 build 932)
|  can send mails only to host supporting smtp-after-pop
|    or simple relaying systems
|
|
v
relay server (Soekris net4501 [486-CPU] running Debian 2.4.27-2-386 )
|  shall collect mails from local network and send them to the ISP (or other provider)
|    using a login at the provider (SMTP-Auth):
|       login with user name
|       provide password
|       send mail
|    against the ISP/provider the relay server shall behave like a client using SMTP-Auth
|
|
v
ISP 
|  sending the mail to the www
|
v
WWW