Outlook cannot conect to Exchange Server using Comcast

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brandon.berndt@gmail.com - 23 May 2008 19:24 GMT

Hi Everyone,

I am currently using Outlook 2007 and cannot conect to my companies
Microsoft Exchange Server. I use Comcast as my internet service
provider. I am able to use our webclient through IE to do my daily
emails, but its really a pain not to be able to use Outlook. So I am
looking for a fix.

When I travel, I am able to connect from hotels (I am guessing since
they don't have any ports blocked) so I know my account is set up
correctly.

I read about comcast "blocking" ports that MES uses to communicate,
but am not able to find a fix for this. So my questions are:

Is there a way around this?
What other options do I have? (ex. getting an at&t wireless internet
card to use from home)
Any other suggestions/tips/info?

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Peter Durkee - 23 May 2008 20:02 GMT

Are you just trying to connect directly to your Exchange server over the
Internet? If so, it's probably your company's firewall that's causing your
problem as much as anything. Your choices of getting Outlook to work are to
either use a VPN and run Outlook through that, or use RPC over HTTP. Check
with your IT department for details.
-Peter

> Hi Everyone,
>
[quoted text clipped - 15 lines]
> card to use from home)
> Any other suggestions/tips/info?

Reply to this Message

brandon.berndt@gmail.com - 23 May 2008 21:16 GMT

> Are you just trying to connect directly to your Exchange server over the
> Internet? If so, it's probably your company's firewall that's causing your
[quoted text clipped - 26 lines]
> > card to use from home)
> > Any other suggestions/tips/info?

I can connect to microsoft outlook web access vie mail.ourdomain.com/
exchange just fine. What I am trying to do is be able to use my
outlook client (the actually application on my laptop) to connect with
MES to receive/send mail/calender/contacts. I can only use outlook for
other email address that are pop3 not MES, since outlook won't connect
to our exchange server (reportedly because Comcast blocks the port)

Reply to this Message

Peter Durkee - 23 May 2008 23:19 GMT

>> Are you just trying to connect directly to your Exchange server over the
>> Internet? If so, it's probably your company's firewall that's causing
[quoted text clipped - 36 lines]
> other email address that are pop3 not MES, since outlook won't connect
> to our exchange server (reportedly because Comcast blocks the port)

I guess it's true that Comcast may be blocking one or more of the ports
needed for an Outlook MAPI connection, but the odds are good that your
corporate firewall is blocking them as well. Connecting via the web client
or by POP3 is comparatively simple as they each involve ports that are
almost never blocked. A full MAPI connection involves a number of ports,
some of which are assigned dynamically, so to allow Outlook to connect using
MAPI through your firewall would require opening a huge range of ports, and
is not considered a good practice.

-Peter

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Peter Durkee - 24 May 2008 00:20 GMT

>>> Are you just trying to connect directly to your Exchange server over the
>>> Internet? If so, it's probably your company's firewall that's causing
[quoted text clipped - 47 lines]
>
> -Peter

So I finally read the part about it working when you're in hotels, so
obviously your firewall isn't blocking those MAPI ports. The best
workarounds are still a VPN connection or RPC over HTTP.

-Peter

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Brian Tillman - 27 May 2008 12:44 GMT

> I can connect to microsoft outlook web access vie mail.ourdomain.com/
> exchange just fine. What I am trying to do is be able to use my
> outlook client (the actually application on my laptop) to connect with
> MES to receive/send mail/calender/contacts. I can only use outlook for
> other email address that are pop3 not MES, since outlook won't connect
> to our exchange server (reportedly because Comcast blocks the port)

Outlook Web Access uses the standard HTTP ports 80 and 443. Whether OWA
works or not has nothing to do with whether Outlook works or not, since they
don't access Exchange by the same method. Peter's correct. It's highly
unlikely that Comcast is blocking any ports because you're not using the
Comcast ports. Comcast blocks specific ports on their own servers and can't
control what ports are available on your company's servers. Your
assumptions are flawed.

Signature

Brian Tillman [MVP-Outlook]

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brandon.berndt@gmail.com - 30 May 2008 07:19 GMT

> brandon.ber...@gmail.com <brandon.ber...@gmail.com> wrote:
> > I can connect to microsoft outlook web access vie mail.ourdomain.com/
[quoted text clipped - 13 lines]
> --
> Brian Tillman [MVP-Outlook]

Hmm, I see. Then what are possible reasons for this issue? Any fixes?

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