External access between organizations




We are managing multiple Office 365 tenants and some are using Teams.


I would like to connect 2 of these organizations so they can chat together and be added to common teams but I'm struggling to do that.


I've followed this guide : https://docs.microsoft.com/en-us/microsoftteams/let-your-teams-users-communicate-with-other-people so I've configured the external access but it still not working, users can't chat with external people. I've also enabled guest access on both tenants but nothing changed.


The operation seems easy but it's not working... I would appreciate if someone could help me, thanks.

21 Replies

Can't you add them to the team either, or is it just the external chat issue? 

Checked the firewall requirement? tried from other location?

Hi, thanks for your answer.


I can add them to a Team as a guest but I'm must enter the complete mail address. It's like there is no connection between tenants.


And I would like to chat with people from other tenants but I can't find them in via the search so no chat possible...


Yes I've tried from different location and there is not firewall filtering....

You add guests by typing their mailaddress..There is no connection directly to any other tenant. There is options to set which domains you want to blacklist/whitelist though


/ Adam

I dont know for sure but it seems this function works for some and for some not! Probably due to this feature is rolling out to tenants bitwise


/ Adam

I have to type the full mail address but it's working even for domain which are not in the whitelist. I think it's because I've enabled guest access.


It's a really strange behaviour and I don't understand why Microsoft doesn't communicate on that point.... While reading the documentation, everything is simple and in real life it's not working.


This is not the first time that there is a bug like this and it starts to be really annoying that Microsoft never reacts to this kind of problem.

Thank you for your help and I keep looking forward for a solution

In Teams, when you create a new message and enter the users email address in the to field, do you see an option popping up that says "search externally"?



Thank you for your answer.


When I create a new chat and enter the complete mail address, I see the option "Search externally" but Teams can't find my contact. I get the message : "We couldn't find this person. Try another email address".

I do have the same!

So, when you click on "search […] externally", what happens then?


I get this:





Same for me, I still can't chat with an external contact...


However domains are in the whitelist in both tenants.

After some tests and verifications, chat with external people is still not working.


But now, I have something strange. When I  create a new chat with an external person, I can write a message it isn't delivered. I have an a error message saying : "This user is unavailable or offline. We've sent an email instead. " But there is no mail sent....


Also I can see the status of my external contact : Available, Busy, Do no disturb... But chat dosen't work.


Any idea ?

Hi! How did you verify that the mail weren't sent? Is it the same if present is "available"?




I made some tests with an external contact.

And I asked him to check if he had receive an e-mail but there is nothing, even in the spam folder.

Yes it's the same behaviour with all status

I would recommend to open a ticket with support via the admin portal.

Hi Thomas,


It's already done but unfortunately, Microsoft support is not able to explain or resolve this issue.


Even worse, they don't know the documentation of their own product.


But I guess, I have to wait...

@Julien Schneider, let's take this offline.

@Julien Schneider was this ever resolved for you?  We are currently having the same issue and we need to figure out how to get this function fully operational.

@Julien Schneider Make sure the admin in the other Teams organization does these same steps. For example, in their allowed domains list, their admin needs to enter the domain for your business if they limit which organizations can communicate with their users.


2. Do you also open external access in OneDrive?