Initial Experience Using eM Client

Kyryll · December 8, 2025, 2:21pm

As new user of eM Client I have to say I’m impressed!
As a software engineer myself, I can imagine how much it takes to build and maintain a software product that aims to compete with Outlook and other enterprise feature parity products without the unnecessary cruft.

I have come across a potential teething issue, though, that I would like some SME expert advise on:
Trying to activate my licence on my work MacBook Pro, I get consistent failures from the app.

My guess is that this is due to my work MacBook is under heavy corporate threat management (endpoint protection, cisco network filtering, dns filtering, etc.).
I have not had this type of problem with any other software I bought that required activations.

Is there anyone on here that has experienced this? I have seen that in some case this is resolved by fixing availability of relevant missing chain certificates. But those articles are about older Windows machines.

Any help would be greatly appreciated.. thanks in advance!

Kyryll

Olivia_Rust · December 8, 2025, 2:25pm

Hi Kyryll,
Could you please make sure the app is allowed to access https://licensemanager.emclient.com/ ?

Kyryll · December 9, 2025, 7:10am

Hi @Olivia_Rust,

Thanks for your response.

I can access https://licensemanager.emclient.com in my browser with no problem.
However, the certificate that my browser “sees” on this domain is the Cisco generated certificate that comes from some network monitoring software.

I suspect that eM Client expects a specific certificate thumbprint when it accesses that URL.
I don’t have control over this network monitoring..

Could please confirm if my assumption is correct and what I can do to register eM Client.

Kind Regards,
Kyryll

Kim_Fisher · December 9, 2025, 11:04am

Hi, we might be able to find out more from licensing logs.

Go to Settings > Advanced.
Enable logging for Licensing under the affected account.
Click the “Clear Logs” button.
Restart eM Client.

Try activating your license.

Go back to > Advanced.
Click the “Send Logs” button.
A new email window will open. Add [email protected] as the recipient, and send it.

Thank you!

Kyryll · December 10, 2025, 1:48am

Thanks @Kim_Fisher!

This cleared things up.

Unfortunately, I can’t just just pass through zips with collected logs, but having had a look inside I can see the pertinent part. I have pasted the extract below. The issue appears to be caused by corporate network monitoring software.

I cannot control how my network traffic in managed and filtered, so if there is no other way to activate eM Client, I would have to look for another option.. alas..

Thanks for your help!
Kyryll

12:39:40.863|006|   eM Client: 10.3.2622.0, .NET: 8.0.18, OS: Version 26.1 (Build 25B78), CPU:Apple M3 Pro
12:39:40.865|006|   
12:39:58.648|00C|   2025-12-10T12:39:58: Unhandled exception in Activate
12:39:58.652|00C|   MailClient.Remote.RemoteCallException: ActivateLicenseFromApplicationEx failed
12:39:58.652|00C|    ---> System.Net.Http.HttpRequestException: net_http_ssl_connection_failed
12:39:58.652|00C|    ---> System.Security.Authentication.AuthenticationException: net_ssl_io_cert_validation, RemoteCertificateNameMismatch
12:39:58.652|00C|      at System.Net.Security.SslStream.SendAuthResetSignal(ReadOnlySpan`1 alert, ExceptionDispatchInfo exception)
12:39:58.652|00C|      at System.Net.Security.SslStream.CompleteHandshake(SslAuthenticationOptions sslAuthenticationOptions)
12:39:58.652|00C|      at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](Boolean receiveFirst, Byte[] reAuthenticationData, CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.ConnectHelper.EstablishSslConnectionAsync(SslClientAuthenticationOptions sslOptions, HttpRequestMessage request, Boolean async, Stream stream, CancellationToken cancellationToken)
12:39:58.652|00C|      Exception_EndOfInnerExceptionStack
12:39:58.652|00C|      at System.Net.Http.ConnectHelper.EstablishSslConnectionAsync(SslClientAuthenticationOptions sslOptions, HttpRequestMessage request, Boolean async, Stream stream, CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.HttpConnectionPool.AddHttp2ConnectionAsync(QueueItem queueItem)
12:39:58.652|00C|      at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
12:39:58.652|00C|      at Microsoft.Extensions.Http.Logging.LoggingHttpMessageHandler.<SendCoreAsync>g__Core|4_0(HttpRequestMessage request, Boolean useAsync, CancellationToken cancellationToken)
12:39:58.652|00C|      at Microsoft.Extensions.Http.Logging.LoggingScopeHttpMessageHandler.<SendCoreAsync>g__Core|4_0(HttpRequestMessage request, Boolean useAsync, CancellationToken cancellationToken)
12:39:58.652|00C|      at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
12:39:58.653|00C|      at Microsoft.Kiota.Http.HttpClientLibrary.HttpClientRequestAdapter.GetHttpResponseMessageAsync(RequestInformation requestInfo, CancellationToken cancellationToken, Activity activityForAttributes, String claims, Boolean isStreamResponse)
12:39:58.653|00C|      at Microsoft.Kiota.Http.HttpClientLibrary.HttpClientRequestAdapter.SendAsync[ModelType](RequestInformation requestInfo, ParsableFactory`1 factory, Dictionary`2 errorMapping, CancellationToken cancellationToken)
12:39:58.653|00C|      at MailClient.Licensing.Client.Generated.Api.License.Activate.ActivateRequestBuilder.PostAsync(ActivateLicenseDto body, Action`1 requestConfiguration, CancellationToken cancellationToken)
12:39:58.653|00C|      at MailClient.Remote.RestApiClient.ActivateLicenseFromApplication(String guid, String hwGuid, String activationKey, String applicationName, String version)
12:39:58.653|00C|      Exception_EndOfInnerExceptionStack
12:39:58.653|00C|      at MailClient.Remote.RestApiClient.ActivateLicenseFromApplication(String guid, String hwGuid, String activationKey, String applicationName, String version)
12:39:58.653|00C|      at MailClient.Remote.RemoteCallsAdapter.ActivateLicenseFromApplication(String guid, String hwGuid, String activationKey, String applicationName, String version)
12:39:58.653|00C|      at MailClient.Licensing.eMClientLicenseSource.Activate(String activationCode, Boolean verify, Boolean invokeUpdate)

Kim_Fisher · December 10, 2025, 2:47pm

Thanks! If you’re interested in further troubleshooting and could get us more information on the Cisco certificate, our developer could advise on what could be going wrong there, but I understand if that’s not feasible. If you’d like to sort out a refund, please reach out to [email protected]

Kyryll · December 16, 2025, 1:03am

Hi @Kim_Fisher!

Thanks for the support. I must say it’s refreshing to see this level of care provided by a software company these days.

As I was wondering whether to keep my licence (for use on just my personal MacBook Pro) or refund it and look for other options.. I noticed an update of eM Client just came through (10.4.4209 (d96494b)).

I can now activate my licence without any problems! No idea if this is part of the update, but I am very happy to be able to use eM Client now.

Thanks for all the help!

Kyryll