title: What is the maximum length of an Azure Active Directory (AAD) username?
body: <p>I'm trying to find the maximum length of an Azure Active Directory (AAD) username. The username is UPN-formatted (username@domain), so presumably there are two string length limits for the username and domain fields.</p>
  <p>All I can find online is the maximum length of either a standard Windows user or a Windows Domain user, which is 20 characters. Is Azure the same? And presumably that's just for the username so what is the limit on the domain string?</p>