"Invalid user name" when you try to create a user name that contains a special character in Office 365

Note

Office 365 ProPlus is being renamed to Microsoft 365 Apps for enterprise. For more information about this change, read this blog post.

Problem

When you create a user name that contains a special character in Microsoft Office 365, you receive one of the following error messages:

Within the Office 365 portal

Invalid user name
Only letters and numbers are allowed. No spaces.

Within Microsoft Azure Active Directory Module for Windows PowerShell

New-MsolUser : Invalid value for parameter. Parameter Name: UserPrincipalName.
At line:1 char:13

Within Exchange Online Windows PowerShell

A Windows Live error occurred while provisioning for "user+invalid_characters@contoso.com". The e-mail name contains invalid characters.

Cause

This behavior occurs because certain special characters aren't permitted in user names that you create in the Office 365. These special characters include but aren't limited to the following:

Property UserPrincipalName requirements
Characters allowed
  • A – Z
  • a - z
  • 0 – 9
  • ' . - _ ! # ^ ~
Characters not allowed
  • Any "@" character that's not separating the username from the domain.
  • Can't contain a period character "." immediately preceding the "@" symbol
  • Can't contain an ampersand (&) character in the user name.
Length constraints
  • The total length must not exceed 113 characters
  • There can be up to 64 characters before the "@" symbol
  • There can be up to 48 characters after the "@" symbol

However, the following exceptions apply:

  • An underscore (_) is permitted anywhere in the user name. This includes at the beginning or end of the name.
  • When creating a group, the number sign (#) can be used as part of the group's name. However, the email address you create for a distribution group or shared mailbox cannot use the # sign.

Solution

When you create a new user in Office 365, make sure that you don't use any of the special characters that are listed in the "Cause" section.

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