NEW Outlook app: how to add an IMAP account with user name different from email address?

The problem is - it looks like your IMAP account name is an email address from these screencaps. That works fine.

The issue is if you have an IMAP account name that doesn't match your email address.

Nothing you've posted has indicated that you're able to add accounts where the login and email don't match.

Specifically - this screengrab seems to show account logins that are email addresses. These are created via the Add Account settings in Outlook (new), which only accepts email addresses for user names, or are imported on the first run of Outlook (new) from Windows Mail.

This screengrab is the Outlook 365 control panel and isn't connected to Outlook (new).

Thank you for sharing your screengrabs - I appreciate it!! - but I think the problem still remains.

Welp...

No resolution on this issue. And - it's after Dec. 31st, so support is now officially discontinued.

Anyone have a good link to uninstalling Windows Mail 10 safely?

Same issue here - shame on you Microsoft. You force the people to move away from "Mail" App in Windows 11 to "Outlook (new)" which is not capable of converting/importing the already configured accounts neither let them be configured manully as you simply ignore that a "Username" or "authentication name" might be different than the Mail address. Prolong the useage of "Mail" as long as it takes you to come out with a working alternative. "Outlook (new)" is not a working alternative, regardless that actually there is no need for you to forward all private mails into Microsoft Cloud. Adding this to you lack of development skills I will switch to "eM Client" - respecting privacy and able to configure correctly. You did everything right in moving people away from using Microsoft tools and apps, well done (as Steve Palmer would say) "Developers", "Developers", "Developers", "Developers", "Developers", "Developers", "Developers", "Developers", "Developers"!

29 Days to go - and still no resolution on this issue.

It didn't make the December "What's new in new Outlook for Windows" list of fixes.

I'm hoping that it will be resolved - but realistically - it's probably not. Shame - there's some features of the new client I'll miss.

You can vote for the feature request at https://aka.ms/AAn65i6.