SharePoint external sharing - external users not receiving email invite?


I've been experiencing a huge amount of difficulty in trying to enable external users access to one of our SharePoint sites. We have a site collection, called 'Projects', and I am attempting to share one of its subsites with a couple of people in another business.


Inside the SharePoint Admin Centre, I've ensured 'New and Existing Users' is enabled in the sharing settings. In addition, this setting is also enabled for the site collection itself. I have tried and tested sharing the site externally with my own personal account and it works fine.


When attempting to share the site with other domains, such as or, the users are receiving nothing to their inboxes (or spam folders). When I share the site I receive no error message in SharePoint, and the user's name does not appear in the 'invitations and requests' area under guest users.


It's also worth mentioning I haven't included any message in the invite, as I know the invitations can have a 256 character limit.


I'd be extremely grateful if anyone can help with this as numerous people are depending on it to access materials held on the site and I cannot find any issues with the setup!

10 Replies

Hi @Toby McDaid ,


When you enter the users email address into the dialogue after pressing the share button on the site does a message appear telling you this user is outside your organisation? 


By any chance are these users already in your tenant as external users?


Kind regards



Hi @Andrew Hodges 


When I first enter the email address before I click the share button I can see a dialogue saying "[email address] is outside your organisation". When I click share, a confirmation dialogue appears in the top-right of the site to say the site has been shared.


I can confirm these users are not already registered with the tenant. I have one account (a gmail one) which I was able to add as an external user many months ago when I first set this up. If I try sharing with that account I successfully get an email invitation, but any other email addresses I've tried (even another gmail one) doesn't have any success.

Hi @Toby McDaid ,


Do you get cc'ed into email saying "Toby McDaid is inviting you to collaborate on <Site name>" .


Any sharing request that goes through successfully should cc you in. If you do get this email you can see that the person you are trying to share the site with is also in the email so then we can assume it is getting blocked at their end, but you can forward the email to them from your address and they can then use that email to access the site. 


Kind regards


Hi @Andrew Hodges 


No, unfortunately I don't receive any CC email which clearly means no invitation is being sent, which is strange considering the site gives me confirmation that it has been shared when I click 'share'. 

Hi @Toby McDaid ,


Last thing I can think of  - did you get an email cc'ed to you with that successful gmail account? If not your end may be blocking 


There might be something that stands out if I was troubleshooting in person but seeing as that screen is fairly standard for SharePoint Online I would raise a ticket with Microsoft as they will be able to view your desktop and see what's happening in the back end. 


Kind regards


@Andrew Hodges 


Originally when I first configured external sharing months ago I did receive a CC email, so it seems as though something has broken since then.


I have logged the incident with Microsoft and scheduled a call with them, so hopefully they can resolve the issue. Will post the solution here if we reach one as I'm sure it could be of interest to others.


Appreciate the help you've provided!




Hi @Toby McDaid,


Definitely sounds like something wonky is going on! Let me know how the conversation with support goes & if you continue having problems, please shoot me a PM so we can troubleshoot further! Thanks!


Stephen Rice

Senior Program Manager, OneDrive

Hi @Toby McDaid ,


I have the same issue, did you get anything useful out of that call with Microsoft?




best response confirmed by Toby McDaid (Contributor)

Hi @Qualle 


It turns out our problem was a bit of a strange one, Microsoft noticed that we had the azureb2b feature enabled on our tenant, which is still in preview. After a colleague of mine disabled this the external sharing seems to work without any issues.


This was the feature causing issues:


Not sure if it would be the same for you but worth checking this out.




@Toby McDaid Has Microsoft provided any information if they will be fixing this and when this feature will be in GA?

I am testing scenario -

Disable "Members can invite guests" in Azure AD (External Collaboration Settings)

Enable one time passcode

In Sharepoint Online Set External Sharing to "New and Existing Guests"

With all this preview setup sites that i share with guests are not receiving any emails.