Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi. I'm Brian and I'll try to help.
Who is your mail provider - that is, what follows the @ in your address. The problem you describe is not a classic Outlook for Windows problem, it's a mail provider problem. You must contact your mail provider to resolve this. If your address uses a Microsoft domain (like @hotmail.com, @outlook.com, @msn.com, @live.com), then contact Microsoft at https://support.microsoft.com/contactus.