office 365 authentication failed

When adding an Exchange Online Plan 1 (Office 365) account I always get a “The server was found, but authentication failed. Check the email address and password”

a) Username and Password ARE correct
b) I have tried adding it as an exchange account instead of Auto-Discovery
c) This works in Outlook as expected with the same credentials
d) is this meant to work in the Free Edition?
e) there is no option to log exchange traffic in eMClient otherwise I would have tried that.

OK, so I have figured out what the problem is, this is actually quite closely related to David’s Post in…

Bottom Line : My machine is in a corporate environment where Windows Server 2008 R2 is answering the auto-discovery requests being sent out and thus supplying me with a wrong authentication realm.

the solution here? For the first setup set your DNS entries in IPv4 to and to force all DNS queries into the actual internet, set up exchange mail on eM Client, then change them back to automatic after this has completed.

Hello Sebastian, glad you were able to resolve the issue, please make sure to let us know if you come across any other issues or questions about the application, we’ll be happy to help.

Thank you,

This solution is quite complex. Paul, can this issue be resolved by eM Client with a software update?

Hello Julien, I’ve noticed this issue on twitter, I don’t think this is what you’re experiencing, what Sebastian above has suggested is not a regular issue and you should not have any issues connecting to your Exchange account hosted on GoDaddy’s servers in case you’re using an Office 365 environment, please try to disable any security software on your computer and check if you’re able to setup the account.

Thank you,

Hello julien, Paul is probably right with his assessment. Note that the dns"fix" only applies in an environment where active directory is present and dhcp is integrated into it. This is not so much an issue with emclient but more how the pc is setup in this environment and how dns queries are answered. Auto setup of (any) mail client almost always works with the help of some carefully placed dns queries.

Hi Paul,

I disabled my security software and added the account, but now I have the Operations Error message of “Synchronizing folder list failed due to the following error: The remote server returned an error: (404) Not Found.”

Our website is hosted by and have to install security certificates for when using Outlook as my email client. Could be causing an issue with eM Client?

To answer your question from another thread, I am using version 6.0.22344.0.

Thank you for your help,


Hello eM Client should be able to use your security certificates from the windows certificate store if they’re valid and available in the store. I’m afraid you’d have to share more details on your certificate setup, I’m not quite familiar with this provider so I can’t really say if the problem is weebly or some other element at this point.

Navigate to Tools > Settings > Advanced and enable Exchange Web Services and Network Communication logging if possible, save the settings, replicate the error and restart the application. After you do so, please navigate to the advanced settings window and submit the logging data to us for more information.


After following Sebastian Meier zu Biesen suggestions I was able to add the account.