I'm trying to share a discussion board with an Exchange distribution list so that the distribution list can receive alerts when the discussion board changes.

However, when I try to share the distribution list SharePoint is giving me this error:

Sorry, you are not allowed to share this with external users.

Everything I've tried to look up about this only talks about SharePoint Online- I'm looking for a solution for on-premises SharePoint 2013.

  • we have a user in AD and while adding that user in the check permissions page we are gettings this error message Sorry, you are not allowed to share this with external users....we are not even trying to add the external user, he is a internal user in AD only.
    – user103608
    Commented May 11, 2022 at 17:54

2 Answers 2


Sorry, but sharing with external users is not available in on-premises. That is a Office 365 feature only.

  • is there an official answer to this? I mean 'sharing external users is an Office 365 feature ONLY'? Thanks.
    – urlreader
    Commented Mar 26, 2015 at 5:04
  • Couldn't find anything except of this documentation which at the end says "Applies To: SharePoint Online"
    – marco
    Commented Mar 27, 2015 at 11:42
  • It's listed in the SharePoint Online Service Description Page (which includes on-prem features): technet.microsoft.com/en-us/library/… Commented Oct 9, 2015 at 16:36

Actually, you CAN share with external users with on-prem SharePoint, but will require implementing ADFS or another PKI / STS solution.

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