Mailstore Home Microsoft 365

Hello. I installed and successfully used Mailstore home a few years ago with Microsoft 365. Since then, we now use Microsoft 365 with 2FA. I’m getting the error “Mailstore is unable to autodetect the server name”. And when I put in the server name (, I’m told “Authentication failed. Check your user name and password.”

I’ve searched and read the posts on the forum that seemed relevant, but none appears to address the issue I’m having.

Here’s what I’ve tried:

  • I created an app password in Microsoft 365 and used it to login
  • Manually entered the Microsoft 365 server name
  • Tried IMAP, IMAP/SSL, and IMAP/TLS protocols in addition to HTTP and HTTPS
  • Autodetecting the host, and manually entering the host (shown in the image at the link above)
  • HTTPS with ‘accept all certificates’ checked and unchecked

We don’t use a proxy server.

I’m guessing the answer is somewhere on the forum, but I wasn’t able to find it. Any help is much appreciated!

Autodetect Error Message

Hi @DaveW001

Not sure if I can help you, but see if you can extract some useful info
from “the horses mouth” .

IMAP is supported, but Exchange is recommended for Office 365.
It so happens that Exchange is available in MSH


Since you already tried Exchange, what is left is to try Modern Authentication as mentioned
in the Ms article.

That’s as much as I’m aware of.

Peter E.


Unfortunately MailStore Home is not currently able to support Microsoft 365’s Modern Authentication.

This is supported for MailStore Server, but the setup process is relatively complicated and can only be completed by the Microsoft 365 administrator, so it is considered too complicated for MailStore Home.

If you can set up app-specific passwords to authenticate via basic authentication then MailStore can be used, but Microsoft is in the process of depreciating basic authentication completely so at best this is a short-term solution.