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Message undeliverable - SMTP on alternate port

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  • Message undeliverable - SMTP on alternate port

    This is the setup:

    one SBS server2003 running exchange
    two network cards; one public network x.x.x.x and one internal
    I know this is not the most secure setup but we have reasons to keep it that way.

    Most of the users access the server from ourside the LAN and their laptops are not joined to the domain.
    they use Outlook configured with IMAP

    We have two SMTP connectors configured. one on port 25 for regular email traffic and one on port 2525 for traffic coming from the Outlook clients (to increase security)
    Everything worked till the other day where some setting got lost so I reconfigured it but I am still having a problem.

    If users send email using OWA everything goes well but if they use outlook the email get bounced with the error:
    "A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients"

    This is telling me that the standard SMTP on port 25 is fine and the connection from outlook to exchange on port 2525 is fine as well. The problem seems related to some internal routing or DNS conflict.

    Any suggestion? I have been trying so many things so far but nothing worked.


  • #2
    Re: Message undeliverable - SMTP on alternate port

    KISS principle would help here IMnotsoHO.
    Using 2 NICs is fine AND more secure if you use the Configure EMail and Internet Connection Wizard with firewall settings
    But just join the laptops to the domain, use Outlook (RPC over HTTPS) and SMTP connectors on port 25 - the wizard even does that for you. It is a perfectly safe setup - unless your passwords are '123abc' or equivalent.
    I have seen too many setups of SBS compromised because admins try to make them "more secure" . So they end up being less secure and costing the company money for lost production because something isn't configured quite right.

    Steven Teiger [SBS-MVP(2003-2009)]
    Iím honoured to have been selected for the SMB 150 list for 2013. This is the third time in succession (no logo available for 2011) that I have been honoured with this award.

    We donít stop playing because we grow old, we grow old because we stop playing.