Hello everyone,

sitemailboxappiconRecently I had to add a site Mailbox to my SharePoint Online site. Something I never had the opportunity to do.

As often, when doing things for the first time, something went wrong.

When I click the icon in the “Add an app” page, I am redirected to the Office 365 app that gives me an error message

The error message said :

the site mailbox couldn’t be provisioned  – String syntax failed validation

As any developer would do, I google this message and click the first link I get https://support.microsoft.com/en-us/kb/2934900

The Microsoft support mentions something about leading or trailing spaces in the title. Not exactly relevant for my case, but then I realize my SharePoint Online Developer tenant was set up with my default language in French (my mother tongue) and my default site collection was provisionned in French as well.

The site title is then”Site d’équipe” with those ugly accents and single quotes that URLs don’t like.

I then simply rename my site as “Team Site” and retry


Looks good! Let’s go to our created Site Mailbox!

Redirected to Outlook again, I have to configure my Outlook tenant (not done until then)

Outlook setup first page (sorry for the french)

It asks me to select the language and timezone and go ahead !

But then, I get this not so clear message

An error message (I guess…) (sorry for the french again)

errorpagetitleShowing more details and taking a look on a page title confirm there is actually an error

Googling that again, I reach this page from Microsoft Support


It seems that, even if, hopefully, I am a Site Collection Administrator of my own tenant, I need to be explicitly added to either the Owners or Members site group.

Let’s do that (Site Settings > Site Permissions > {Owner group} > New  > {Add your name}


When I reopen the Site Mailbox, I still encounter the same issue, but maybe you noticed (if you speak french) that the unclear error message above said something about retrying after 15 minutes.

Let’s take a long coffee 😀

(~ 15 minutes later…)

I reopen the Site Mailbox and then

The site Mailbox is created


Here we go, I hope it will help some of you

See you soon !