Some Office 365 accounts experience errors connecting to Xendo which is caused by an "SMTP matching" problem.
This appears to affect Office 365 accounts that were originally created on-premises and then migrated or transferred to Office365. The "SMTP matching" issue arises when SMTP address on Office365 doesn't match with the user's account identity as defined in Active Directory (AD).
According to a Microsoft Knowledge Base article (http://support.microsoft.com/kb/2641663), these steps may resolve the issue:
- On Office 365 Global Admin, check the user account to make sure the SMTP address has the match email address for the user's Office 365 login.
- Then check to make sure the user's SMTP address has MailBox associate with it (and is assigned with an Exchange/Office365 Mailbox).
See attachment screenshot for the admin settings page: