A few weeks ago some users reported issues with email searches as Outlook returned 250 results maximum.

I usually dont perform big searches in my mailbox so I didnt know if I also had the problem but after some tests I realized that several factors came into play:

– Outlook option to limit searches

Outlook - option improve search speed limite results

To allow big amount of results (>250) Its essential to disable the check "Improve search speed by limiting the number of results shown"
However, applying the change to the involved users didnt solved the problem for some of them.

– Cache Outlook
In addition to changing that option, I tried by doing changes to Outlook cache

Cache disabled – The results never exceeded 250 results.

Outlook - cache disabled
Outlook - items result 250

The entire mailbox cached – The issue is fixed aparently.

Outlook - cache items keep offline alll
Outlook - items result 11000

Cache enabled but not for the entire mailbox – At first it returned results greater than 250

Outlook - cache items keep offline

But if clicked the option to search more Exchange server results are reduced to 250 again!

Outlook - cache view more items
Outlook - items result 250

– Exchange 2013 bug

So that when Outlook needs connection to the server to perform the search the issue appears.

I finally found that there was a reported bug in Exchange 2013:

A few weeks ago there was no fix, but with Exchange 2013 Cumulative Update 11 (released on 15 December) it seems to be solved.
Exchange 2013 – CU 11 released – SomoIT

So, to solve the problem update to CU11 (update scheduled in January for my Exchange 😀 ).
While not updated, as workaround you can use the cache feature to avoid the bug.

[UPDATE Jan 11 2016]

Just installed Exchange 2013 CU11 and the issue still not solved for me 🙁

[UPDATE Feb 05 2016]

I have opened a case. Microsoft has confirmed me that they have been able to reproduce the issue on a lab with Exchange 2013 CU10 and after installing the CU11 the issue is not fixed.
So confirmed CU11 does not fix  KB3093866

[UPDATE Feb 11 2016]

The assigned tech (after consulting development team) indicates that an additional configuration is needed:
See my post: Exchange 2013 – Solved the “Search results limited to 250” bug