Authentication suddenly failing

On many occasions in the past, the client failed accessing the email servers, giving me the “password required” alert. Usually, clicking OK was sufficient. I’m talking about regular IMAP/SMTP connectivity. I won’t say anything about the constant issues accessing gmail accounts.

Today, all my accounts get the failing authentication. The passwords were not changed overnight, and I checked with online tools that they are still correct.

I re-entered them (almost 10 accounts), restarted EM, restarted the computer. I still can’t access my emails. 

Do you know what it suddenly can stop working? Thanks for your help!


Hi, what version of eM Client are you currently using?
Have you by any chance adopted a new antivirus/firewall/proxy software that might be blocking the connection?

Thank you,


I’ve been using ZoneAlarm for a long time. I disabled it for testing but the issue persists. No proxy used.
The em version is 6.0.20154.0.


Can you please go to Tools > Settings > Advanced and turn on IMAP logging for your account?

  1. Save the settings
  2. Restart the application
  3. replicate the issue
    when the popup box with “authentication failed” appears, please go back to the advanced settings window and click on “send logs” and send the logs to [email protected]

Also please include a reference link to this forum topic.

Thank you,

For what it’s worth, this has just started happening to a customer of ours who is trialing em Client for rollout across their company. Other software can log in using the same account details, but the CRAM-MD5 authentication details sent by em Client are being refused by the server. It was working fine until a couple of days ago, and then just stopped.

Hi again Luke, can you please tell me what mail service you’re using?
Are you by any chance using

Thank you,

Hi, what mail service is your customer using? Is he by any chance using
If not, can you please advise him/her to use the above instructions and send me the logs from this issue?

Thank you,

No, they’re not using

I notice it looks like an update has been released which looks relevant:

6.0.20498.0     (11/06/2014 13:15:59)- Fixed CRAM-MD5 and several other authentication schemes on IMAP

Is that meant to fix this problem?

I was trying to determine whether you have the same issue that this fix was released for,
you can try to download and install the update and check if it solves the issue.

Thank you,

The update fixed the problem - thanks

Great, glad that it works, let us know if you come across any other issues or questions, we’ll be happy to help.

Thank you,

I have got a problem with “Authentification Failed” when I try to read or send mail. EM Cient asks for the user and password, but it has not been changed.   I have tried re-entering them and that was useless.   I am sending and receiving via a dedicated mail server, but other users are also sending and receiving successfully from the same server without a problem?  Is there a setting I need to refresh or change?

Hi Peter, what version of eM Client are you currently using and what mail service are you using?

Thank you,

I am having the same problem with Gmail. 

Hi Michal, are you using two step verification on your Gmail account? If not, please try to access this setting, and set it to enable, after you do so, check if the issue persists.