Sharing Exchange 2010 calendars with people outisde our organization

Not open for further replies.


Senior Member
Outlook version
Email Account

We have a 2010 Exchange Server in which we have 2 calendars that are tied to two conference rooms.

There is another company in our same building that also uses those conference rooms and they need to see the busy/free information and need to be able to reserve those rooms as well.

Can they accomplish this even if they are not part of our netowrk and do not have an Exchange server?

Before we had the Exchange server we used to use gmail and the google calendar sync tool but now they are history.

Thanks and help is appreciated.
They won't need an account to reserve rooms (the room needs to be configured to allow outside addresses to create meetings) but I'm not sure if they can see the availablity service. I'l check on it.
Ok Diane that variable is already set to TRUE and is working somehow.

Now I am having a different problem. I am testing with another PC in which I have configured my IMAP Gmail account.

The company that would be sharing our conference rooms uses POP3.

I was able to add the ics calendar to Outlook but everytime the other person (in this case me) tries to reserve a room 2 things happen:

- Outloook does not detect conflicts. Could this be because they are outside our organization and not using Exchange?

- The ics calendar in Outlook always shows tentative instead of busy whenever I send the invite using the conference room's email address.

Thanks for your help
Same thing if I try to reserve a room at the same time in which the other company has already reserved it, it reserves it anyway and does not detect the conflics.
The resource needs to be configured to automatically accept and to decline conflicting. Open the mailbox in outlook and configure it in Tools, Options or use a cmdlet - same one as fbefore, but parameter is AllowConflicts = false.
OWA2 says eents from exxternal users are not processed - that needs to be enabled.
Ok that option didn't make any difference.

Everytime an external sender sends a meeting request it is placed on the resource calendar as Tentative and in order to change to busy I have to go to the resource mailbox through Microsoft Outlook, double click on the meeting request entry and manually click Accept. When I double click it says Please respond.

As soon as I click on Accept the status changes immediately to busy.

I'm not sure if the following work arounds is what I'm looking for: (I think this solution is only for Exchange 2007 and should not be needed in 2010).

By the way the other company does not have an Exchange server.

Does it has to do with Organization Relationships and Federation Trusts?
I believe the second TechNet article is the key - I'm going to test it on my server next.
After, oh, 200 meetings, I finally got it. :) - i created a receive connector and entered my outside accounts mail server ip. On permissions, I used Exchange Server and External on the Auth. tab.

Not sure if it helped, but I also have a user account in Exchange for the outside address - it may not be necessary to do this.
So if the other company uses a POP3 godaddy email account should I add their pop ( and smtp( IP addresses to the receive connector that I have to create?

What about the local IP address and port? Should those be the same that are configured for the default mail receive connector?

I'm using Exchange 2010 by the way.

Don't know if that article applies to that version.
I'm testing it on my exchange 2010 server...

You need to use their SMTP IP, not the address. I don't know how many SMTP addresses go daddy uses, you might need to add a wide range of IP addresses, which is less secure.

Look in the header of a message they sent you - get the ip from there. I'll check mail from my godaddy accounts and see if it varies much too.

I'm also checking to see if I can find another way to do it that uses their address instead...
I'm done working on this for the night - I can't get any thing else to work. Oh, and in addition to the receive connector, you need to create a Mail User for the account. If there are only a few people reserving the room, its workable, but if there are a lot who can access it, going with tentative and instructing your users to treat tentative as booked might be the best option.

(It might be possible to have one user and everyone's address on it - but it's still not very workable with a lot of users.)

Another option is to create a mailbox on exchange for them to use when they book - you can configure it so they can't send much email so they can't spam from your company.
Not open for further replies.
Similar threads
Thread starter Title Forum Replies Date
B Sharing Multiple Outlook 2010 Calendars (Exchange) Exchange Server Administration 4
A Network Permissions for sharing calenders between exchange severs Using Outlook 1
D Sharing BCM data with Exchange BCM (Business Contact Manager) 1
O Outlook on Android: after sharing / sending a news article, draft remains open. Why? Using Outlook 1
Fozzie Bear Sharing Birthday Calendar Using accounts in Outlook 3
L Sharing Calendar for Only Scheduling Using Outlook 2
GregS Simple calendar sharing doesn't work Using Outlook 6
B Sharing Outlook calendars gone wrong Using Outlook 0
D Sharing calendars in Outlook 2016 Using Outlook 1
D Sharing calendars Exchange Server Administration 1
Diane Poremsky Sharing Outlook Calendar and Contacts Using Outlook 0
Diane Poremsky Sharing Calendars Using Outlook 0
Diane Poremsky More Tools and Utilities for Sharing Outlook Data Using Outlook 0
Diane Poremsky Sharing Outlook Calendar and Contacts over the Internet Using Outlook 0
O Calendar Sharing - From This Date On? Using Outlook 1
M Sharing of BCM database across the internet BCM (Business Contact Manager) 2
Chris Grew Sharing BCM Database BCM (Business Contact Manager) 6
M Blank Pop-up Window when click "Manage Sharing" BCM (Business Contact Manager) 1
J DisablePST = 2 : Only Sharing-Exclusive PSTs can be added Using Outlook 1
J Outlook 2007 Error sharing Calendar: Error while preparing to send sharing message Using accounts in Outlook 2
J Sharing outlook, Office 2013 Home Premium Using Outlook 8
A Sharing calendar Using Outlook 1
M Workarounds for sharing custom Outlook 2007 forms? Using Outlook 3
B Sharing Additional Calendars Using Outlook 1
A Need Help with BCM2010 Sharing on outlook 2013 Scenario! BCM (Business Contact Manager) 1
S Sharing Outlook 2013 without a server Exchange Server Administration 1
J Sharing Contact w/ a custom form Using Outlook 3
D Sharing BCM with laptop. BCM (Business Contact Manager) 4
D Sharing Categories on Appointments Using Outlook 0
V Sharing Hotmail contacts / groups not working as expected Using accounts in Outlook 1
B Sharing Contacts via Live Using Outlook 2
J Company calendar sharing problems Using Outlook 2
B Outlook Calendar Sharing - Multiple Time zones Using Outlook 1
R Simple Sharing of Outlook Profile Using Outlook 1
M Remove sharing icon from outlook contacts Using Outlook 6
L Sharing Outlook data Using Outlook 1
G Sharing Business contact manager BCM (Business Contact Manager) 5
U Trouble for sharing Calendar Using Outlook 3
S Calendar sharing problmes between Outlook 2007 & 2010 Exchange Server Administration 0
H Outlook 2010 : Error while preparing to send sharing message Exchange Server Administration 8
J Joint Calendar Sharing - Editing Using Outlook 1
A sharing calendars Using Outlook 1
B sharing contacts BCM (Business Contact Manager) 1
S Sharing BCM contacts within Workgroup, Leads and Projects BCM (Business Contact Manager) 5
D Sharing BCM Database with other computers on a network BCM (Business Contact Manager) 1
R Outlook 2010 calendar sharing not working Using Outlook 3
R BCM 2010 Beta - Sharing issues BCM (Business Contact Manager) 1
S Sharing BCM contacts and linking items to records BCM (Business Contact Manager) 1
D 2d help request-problems sharing BCM database BCM (Business Contact Manager) 1
H Outlook/BCM hangs when using the assistent for sharing a database BCM (Business Contact Manager) 2

Similar threads