Often it is the company name portion of the account name that makes it too long ( .). If you log into panel.alentusoutlook.com and change your Company Name/Details, then your usernames should change. We recommend you change your company name (on the setup screen) to a one word. For Example: Instead of “TheBigMailExchangeCompany” enter “BMEC” or some similarly short name in the company name field.