first thanks for this great piece of software.

==== Required information ====
- iRedMail version: 0.8.3
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: Debian 6.0.6 32bit
====

I run a Debian 6.0.6 homeserver at my place which is connected via DSL to the internet. It has a dynamic IP.

Hostname: homeserver
Domain: myexampledomain.eu

I setup iRedMail which runs fine so far: I can send and receive emails from my postmaster@myexampledomain.eu email account.

The problem: Not all of my sent emails reach their addressees! Email provider like GMX.de or WEB.de decline receiving my emails which seems to be a general problem with dynamic IP addresses although the MX lookup for my domain points correctly to myexampledomain.eu (N.B. Other providers accept my emails without objections!)

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Example sender mail log for refused emails:
homeserver postfix/smtp[2480]: 7E8AFC273A: to=<xxx@gmx.de>, relay=mx1.gmx.net[213.165.64.102]:25, delay=4589, delays=4589/0.19/0.28/0, dsn=4.4.2, status=deferred (lost connection with mx1.gmx.net[213.165.64.102] while receiving the initial server greeting

homeserver postfix/smtp[2481]: 260ACCD43B: to=<xxx@web.de>, relay=mx-ha03.web.de[213.165.67.104]:25, delay=423, delays=423/0.1/0.24/0, dsn=4.0.0, status=deferred (host mx-ha03.web.de[213.165.67.104] refused to talk to me: 554-web.de (mxweb001) Nemesis ESMTP Service not available 554-No SMTP service 554-IP address is black listed
++++++++++++++++

I want to solve that problem (except you have a better solution) by sending via the smtp server of my privat email account at Arcor.de.

Question:
How to configure iRedMail to use a smtp relayhost for sending all emails?

SMTP: mail.arcor.de
User: myaddress@arcor.de
Password: [mysecretpassword]

(Sasl authentification necessary)

I have done this before configuring postfix with relayhost on systems WITHOUT iRedMail, but is there a step-by-step tutorial for iRedMail? Unfortunately I am absolutly new to LDAP.

Thanks for all help.

Alf