Off site clients connecting via IMAP on outlook cannot send mail to outside domains, error relaying not allowed.

Posted on 2008-09-29
Last Modified: 2013-11-30
Trying to setup exchange and smtp for users who will connect via outlook or mac mail to the exchange server with imap.  I can get the users logged in to recieve mail and sync folders but sending via smtp fails.  If I use no authentication the user can send mail to internal addresses but external addresses come back with no relay allowed.  If I try to setup outgoing mail server authentication on the clients they do not connect to the outgoing mail server, it keeps saying incorrect username or password.  I have tried every variation of domain\username, username, and username@domain I can think of.

This is a new installation of exchange 2003 on a SBS.
Question by:InvisibleTerror
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Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 22599116
External users with Outlook shouldn't be using IMAP, they should be using RPC over HTTPS.  This feature must be enabled in the Configure Email and Internet Connection Wizard (CEICW -- which is linked as Connect to the Internet in the Server Management Console > To-Do List) by checking the box on the Web Services Configuration Screen for "Outlook via the Internet".

A visual how-to is here:

Port 443 must be open on your router/firewall.

Then RPC over HTTPS client configuration instructions are on the server's Remote Web Workplace main menu -- linked as "Configure Outlook via the Internet" -- access the RWW Main Menu by going to http://localhost/remote from on your server.  (See for more info on RWW).

A full overview for SBS based RPC/HTTPS configurations is here:

For Mac users, you might still want to use IMAP, but I'd suggest they use OWA instead.  If you insist on IMAP then you need to set their outgoing server to their ISP's and not allow relay through your SBS/Exchange server.


Author Comment

ID: 22599169
Sorry I was tying to take a shortcut on this.

When I say outlook, I am using outlook to test this.  The 2 users that will be connecting with thier laptops are on macs using mail, which I don't have to test with.  If I had a client using outlook I agree rpc would be the way to go.  

I can't set it up to use thier isp's smtp because they only allow connection to smtp if you are on thier network.  So I need to setup smtp on exchange.  I do not want an open relay so I would like some setup of authentication.
LVL 74

Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 22599474
That's why I suggest that they user OWA instead.  Since Mac Mail can't deal with Contacts and Calendar, it would make more sense to use OWA.


Author Comment

ID: 22599499
I agree with that as well but that answer does not work with my client.  He has 2 email accounts on his mac mail and doesn't want to use something different.  
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Accepted Solution

Michael W earned 500 total points
ID: 22600188

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