IMAP and SMTP with Exchange

I have a user that is not part of the domain (he could be, but he's never on the main network, does not use VPN, etc.) but still needs to access and send emails using the company domain name for which our Exchange 2010 server is authoritative for.

IMAP for receiving mail works just fine, but SMTP for sending mail does not (receive a failure message stating the connection was interrupted).  I was able to setup IMAP on multiple Blackberry's, and they can all send and receive fine.

Curious what I need to do to allow this user to access the SMTP server from his Outlook client and send emails.

Ports are allowed and forwarded within the Cisco ASA; firewall within Windows is set to allow SMTP. SMTP service (as well as IMAP) is started. The local ISP actual receives our mail, filters it via a Barracuda, uses LDAP for authentication, and delivers via SMTP.  

Do I need to set up a special type of connector?
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Alan HardistyCo-OwnerCommented:
Why not setup Outlook Anywhere instead, then you don't have to worry about SMTP access.
TercestisiAuthor Commented:
Well, I just found out via further testing that the ISP he is on is blocking port 25.

How do I setup SMTP to listen and accept connections on alternative ports?
You need a receive connector on Exchange 2010 that allows 'Authenticated Users' and is accessible from outside world.

The important note thre is that the permission group needs to allow users to authenticate and the user then needs to enter their username/password combination to relay email.


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Alan HardistyCo-OwnerCommented:
Setup Outlook anywhere which uses TCP port 443 and you don't have to worryabout ISP's blocking ports to protect from spam.
TercestisiAuthor Commented:
From what I understand, I'd need the computer to at least be on the domain to connect it to the Exchange server and setup Outlook Anywhere; I don't really have that option at this time, but will look into it for the future.

In the mean time I created a new receive connector on an alternate port with the permission group set to authenticate only to our domain/Exchange users; everything worked well.
Alan HardistyCo-OwnerCommented:
Outlook Anywhere does not need the computer to be connected to the domain for it to connect.

It also means you don't have to worry about port blocking, setting up receive connectors or opening up extra ports.

IMAP / SMTP is a very inferior solution to Outlook Anywhere.  All you need is a working internet connection and your password.  No ISP will bock port 443 and thus you won't get problems with it.
TercestisiAuthor Commented:
I attempted to setup outlook anywhere following the technet instructions you linked to, but the instructions stated that I needed to enable secure http (443) on an already existing Exchange account; since there is no existing Exchange account, it seems I would need to bring the laptop on to the domain and connect.
Alan HardistyCo-OwnerCommented:
All you need is to open TCP port 443 on your firewall, a valid SSL certificate from a 3rd party Certificate provider, a server configured correctly and a correctly configured client and you have a remote user who can use Outlook as if they were sitting in the office, with all the usual features available including Calendar sync, Contacts sync, Email sync and Tasks sync, plus Out Of Office (OOF), shared calendars etc.

Visit to test connectivity.

Run the Outlook Anywhere test.

Under no circumstances does the client need to be part of the domain.  How do you think Exchange hosting works?  If all customers of Exchange Hosting companies have to join the hosting companies domain, it just wouldn't work.
Alan HardistyCo-OwnerCommented:
My home computer is not part of my home domain and it uses Outlook Anywhere to connect to my home Domain (Exchange 2010).
TercestisiAuthor Commented:
Thanks; I will check it out.
Alan HardistyCo-OwnerCommented:
No problems - just trying to offer you best practise advice rather than just answering your question (not that there is anything wrong with just answering your question).
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