Outlook.com, AirSync, EAS?

I open
this topic under Questions as I am not sure if it concerns a real problem / bug or if it is just some misunderstanding from my side.

I am using eM Client 7.0.27943.0

I want to use it as a client for my Outlook.com account which has been migrated recently to the new functionality / interface / synchronization mechanism. 

The way I understand things from the discussions on this forum is that it is preferred (or perhaps even required??) to use Mail / Exchange in stead of the Automatic Setup when preparing eM Client for the new Outlook.com protocols. 

When I use the Mail / Exchange setup routines eM Client properly syncs mail and calendar data but it seems to choke at the contacts data. It pops up an error message, and under Operations / Log I see:

18:44:15   MailClient.Storage.Application.OperationException: Synchronizing folder ‘Outlook EAS/Contacts/’ failed due to the following error: Invalid data source operation., There was a problem accessing Active Directory. Check your network connections and try again. —> Microsoft.Exchange.WebServices.Data.ServiceResponseException: Invalid data source operation., There was a problem accessing Active Directory. Check your network connections and try again.

However, when I use the Automatic Setup routines it ends up with IMAP / SMTP / AirSync  services and everything works normally. No error messages and mail, calendar and contacts are properly synchronized.

As I can get things to work I would say this is not a problem, however, I don’t understand what is going on.

Is it some setting I have to change, is it something on Microsoft’s side, or am I just misunderstanding the way it is supposed to work?

Thanks in advance for enlightening me!

Hello Herman,
AirSync, while it still work on some server sometimes, it is not officially supported by Microsoft and may cause issues.
IMAP/SMTP is great solution if you want to use mail only and do not need to keep your calendar and contacts synchronized, otherwise exchange is recommended.

I believe the error is triggered by a Distribution list, we have seen this error before and are working on resolving it.
If you could perhaps provide more information about the DLs you have (or even forward the DL for analysis to rust@emclient.com) it would greatly help us in resolving this issue/adapting to it.


Hi Olivia,

Thank you for responding.

Also thank you for your hint about Distribution Lists which may be at the root of this problem.
I have a couple of “Contact Lists” as they are now called in Outlook.com.
Also, in eM Client I have some of my contacts assigned to self-defined categories.

Unfortunately I am not at liberty to send the contact details to you.

Anyway, I will try to re-define my Contact Lists and eM Client categories to see if I can get it to work with an Exchange set-up.

I will keep you posted,

Best regards,


Hi Olivia,

As promised in my previous post, a follow-up.

I have got it to work, I can confirm that your idea that the error is triggered by a distribution list is correct.

Here is what  I did:

  1. in eM Client I unassigned all contacts from eM Client categories while I was still using the AirSync setup
  2. deleted the Outlook.com account in eM Client and created a new one via the Exchange setup routine.
    3.  syncing seemed to work but extremely slow, in the end the contacts did not sync
  3. in Outlook.com I removed al Contact Lists (distribution lists)
  4. now the contacts sync OK as well
  5. from here on it seems that a new contacts list added in Outlook poses no further problems.
  6. it also seems that a new list added in eM Client poses no problems.

I want t do more testing  re. 6. and 7. , this was what I could do in the spare hour I had.

Hope this helps,

Best regards,


Hello Herman,
thank you very much for sharing your solution here on the forum where it can help other users who might experience this issue as well :slight_smile: